Buying MK4 GTi for trackday use, need your help to take it to Sti/Evo level!

[DLDL]

Hi all,

I am buying a MK4 GTi for trackday use, and I want to upgrade it to a very competitive level, close to STi/Evo, without spending so much. I know, the not spending much part is a huge constraint. But that´s the beauty of it.

I´ve done a ton of research on the forum and on performance providers websites and I have an idea of what to do. Can you help me here with your thoughts? I´d appreciate it!

Some faq:

0) no, I´d not rather buy a STi or Evo, and I cannot buy a R32 or VR6 or a MK5 or MK6. GTi MK4.

1) this is not my first trackday car, dont be worried about me getting seat time

2) I know this is a long term project, and should be done bit by bit. But I am leaving the country shortly, and need to buy all the equipments and parts for this project NOW.

3) I have a good budget for it, but will spend considering the "performance added per dollar spent".

Therefore I ask you to focus the discussion on:

- is this setup good enough?
- what would you add/remove (considering "performance added per dollar spent")?
- where to buy it cheap?

thank you very much

Daniel

1) Brakes
a) Upgrade front to 12.3" and rear to 10.1" slotted rotors,
b) track pads (EBC yellowstuff or Hawk HPPlus),
c) Motul brake fluid
d) brake lines
Question: I am not planning to change calipers and carriers. Do I need it, and is it worth it?

2) Suspension
a) Bilstein PSS9 (I need something adjustable, to run street as well - wife is going to drive)
b) Rear anti-sway bar (neuspeed?)

3) Tires/wheels
a) 225/45-17 Hankook RS3 tires (slicks wear out too quickly, much more expensive to maintain)
b) 17x8 wheels (anything cheap. ideas?)

4) Engine/power/transmission
a) 3" Eurojet cat-back Exhaust (cheapest one I found)
b) Bigger turbo + remapping (which one???). looking for 300whp max
c) TIP
d) SMIC upgrade
e) LSD (Wavetrac)

[zooyork155]

Being budget conscious you should put your dollars into track time with the car first. This will make you a faster driver and as you become more familiar with the car you can begin to modify your setup as you need it.

It will be easier and more efficient (in terms of time and money) for you to get fast this way.

Slapping a bunch of quickie mods on may just hurt your learning curve and blow your budget.

[DLDL]

Thank you very much for your answer. Let me clarify this for everyone:

1) this is not my first trackday car, dont be worried about me getting seat time

2) I know this is a long term project, and should be done bit by bit. But I am leaving the country shortly, and need to buy all the equipments and parts for this project NOW.

3) I have a good budget for it, but will spend considering the "performance added per dollar spent".

Therefore I ask you to focus the discussion on:

- is this setup good enough?
- what would you add/remove (considering "performance added per dollar spent")?
- where to buy it cheap?

thank you

[mgyip]

1) Brakes
a) Upgrade front to 12.3" and rear to 10.1" slotted rotors,
b) track pads (EBC yellowstuff or Hawk HPPlus),
c) Motul / ATe SUPER BLUE brake fluid
Question: I am not planning to change calipers and brake lines. Do I need it, and is it worth it?

Skip the slotted rotors and upgrade to a better pad. Don't know much about EBC other than most Track Junkies don't use them. Hawk HP+ is a nice aggressive street pad - go with something better such as their DTC compound. Also change lines to improve brake feel and also to reduce the chance of exploding a brake line under heavy braking.

[Mmack]

From experience tracking a 20AE, here were the highlights of my setup:

Handling:
Big RSB - I had an Autotech and was very happy with the mounting hardware and general design. Not sure there's a huge performance difference among the various options out there.

H2Sport Spindles - a must if you want your car to turn without howling like a banshee. These things are pricey and invisible, but worth every penny. Totally transformed the car. (!!!!!)

Also got some LCA busings from an Audi TT (I believe) which were a direct swap, but had more metal, less rubber. (Don't qoute me on this one -- have a look and see what's out there.)

I ran a Ground Control setup with custom-valved Bilsteins to match the spring rates. Ground Control camber plates. (Still have em.) A little much for the street though.

Shifting:
If you can get a 6-spd (20AE or 337), get one. (Couldn't tell from your post whether you've narrowed in on a specific car or not.) And replace the "dogbone" mount with a polyurethane piece. Huge gain in shifting precision.

Power:
Believe it or not, for as much as I had into suspension, my car was never chipped. Reason: it was pointless until I got a big intercooler (which I never did before selling the car). The stock intercooler would heatsoak and power would fall after a few laps around Sebring. I was leaning toward a bigger side-mount, as I liked the idea of less tubing, faster throttle response. All theory -- I have no insight on which intercooler is better.

Brakes:
Lots of good intermediate track pads out there. The 20AE and 337s are blessed with pretty big brakes (I have no experience with the standard Mk4s). With some track pads (I believe I used Mintex C-Tech, and I've heard good things about the other pads mentioned) and Motul fluid (skip the super blue), you should be good to go. Oh, most track pads don't have brake wear sensors, so the light will be on your dash. Be wary of pads that are hard on rotors, they'll ruin your wheels. Quickly.

Also had a set of solid caliper guide busings (if that's the right term) from TyrolSport. Seemed to help brake feel and pad life.

Wheels:
I ran 5-Zigen FN01RCs (I think that's the model), 17x8, and around 17lbs each IIRC, which is pretty light for the size. Still have them in my garage, in good condition, and they need to find a home. If you get an 8" wheel, your're better equipped to run either 225s or 235s. The latter is a little wide for 7s.

Enjoy your new car!

Mmack

[2 doors]

I'm going to echo some of the others.

Brakes: Plain rotors are fine, but get good ones like Zimmermans. The 12.1" front/1 10.1" rear is a good upgrade. I run Hawk Blues. Grippy and pretty cheap. The TyrolSport bushings are a good idea, as are lines. I second the Motul fluid. Super Blue made my clutch pedal squeak.

Suspension: Add camber plates to your list. Koni yellows are on sale now. Ground Control makes coilover sleeves for this application. Look into that. Big rear bar is a must. (I have Shine). TT LCA bushings are a cheap upgrade. My Neuspeed lower tie bar livened turn-in.

Wheels/Tires: I agree - 7's are too narrow. Go for 8" wide with 35mm offset. You can run 225, 235 or 245 then. Peruse the classifieds and get a second set with R-comps for track only duty.

Engine: As you've stated, bigger turbo will need bigger exhaust and IC. Consider just a chip and exhaust first and then save for bigger turbo after you've sorted the rest out.

You neglected to mention the trans. A LSD of some type will be required before upgrading power or you will just roast the inside tire on corner exit. Wavetrac seems to be a good choice. I went with a TT short shifter and a billet steel VR6 flywheel and clutch for quicker revs as well.

Forget about catching STI's & EVO's with this setup. Either of those with a driver equal to your skill level will stomp you. You may be able to keep up with older WRX's though. I'm not saying a MkIV can't be made to keep up, but it will take a LOT of work.

The Classifieds are your friend. I sourced my complete 337 brake setup from there and both sets of wheels I currently have now, along with various other bits.

[rex_racer]

The setup you listed is not good enough. Assuming you have plenty of track experience as you have already stated, it would be cheaper to look at a well sorted car to begin with. I actually happen to know of one for sale that is setup for just that. Which side of the country are you on?

[Mmack]

There's a sweet mk5 street legal track car FS in Florida. DSG, but it's quick and seems well sorted.

[3lfk1ng]

On the super cheap:
Weight: Gut the car
Suspension: Get rid of every rubber bushing possible. Get PSS9's
Power: Chip it

[DLDL]

Don't know much about EBC other than most Track Junkies don't use them. Hawk HP+ is a nice aggressive street pad - go with something better such as their DTC compound. Also change lines to improve brake feel and also to reduce the chance of exploding a brake line under heavy braking.

thxs. just added brake lines.
QUestion: what pads to use on track? Hawks are more expensive than EBCs.

H2Sport Spindles - a must if you want your car to turn without howling like a banshee. These things are pricey and invisible, but worth every penny. Totally transformed the car. (!!!!!)

Also got some LCA busings from an Audi TT (I believe) which were a direct swap, but had more metal, less rubber. (Don't qoute me on this one -- have a look and see what's out there.)

I ran a Ground Control setup with custom-valved Bilsteins to match the spring rates. Ground Control camber plates. (Still have em.) A little much for the street though.

Shifting:
If you can get a 6-spd (20AE or 337), get one. (Couldn't tell from your post whether you've narrowed in on a specific car or not.) And replace the "dogbone" mount with a polyurethane piece. Huge gain in shifting precision.

Also had a set of solid caliper guide busings (if that's the right term) from TyrolSport. Seemed to help brake feel and pad life.

Wheels:
I ran 5-Zigen FN01RCs (I think that's the model), 17x8, and around 17lbs each IIRC, which is pretty light for the size. Still have them in my garage, in good condition, and they need to find a home. If you get an 8" wheel, your're better equipped to run either 225s or 235s. The latter is a little wide for 7s.

Mmack

thanks a lot, all very good points!

camber plates: lowering 2" already gives -1o. isnt it enough? do I need it? What about rear shims? I was not plannign to do these.
Added LCA bushings. I think I will do motor and transmission mounts as well. Caliper bushings may be too much.
Not sure about spindles though. I did some research, and think it adds complexity without that much benefit. thoughts?

PM me with the parts you have, their conditions and price. thanks!

Brakes: Plain rotors are fine, but get good ones like Zimmermans. The 12.1" front/1 10.1" rear is a good upgrade. I run Hawk Blues. Grippy and pretty cheap. The TyrolSport bushings are a good idea, as are lines. I second the Motul fluid. Super Blue made my clutch pedal squeak.

Suspension: Add camber plates to your list. Koni yellows are on sale now. Ground Control makes coilover sleeves for this application. Look into that. Big rear bar is a must. (I have Shine). TT LCA bushings are a cheap upgrade. My Neuspeed lower tie bar livened turn-in.

Wheels/Tires: I agree - 7's are too narrow. Go for 8" wide with 35mm offset. You can run 225, 235 or 245 then. Peruse the classifieds and get a second set with R-comps for track only duty.

Engine: As you've stated, bigger turbo will need bigger exhaust and IC. Consider just a chip and exhaust first and then save for bigger turbo after you've sorted the rest out.

You neglected to mention the trans. A LSD of some type will be required before upgrading power or you will just roast the inside tire on corner exit. Wavetrac seems to be a good choice. I went with a TT short shifter and a billet steel VR6 flywheel and clutch for quicker revs as well.

The Classifieds are your friend. I sourced my complete 337 brake setup from there and both sets of wheels I currently have now, along with various other bits.

Great, thanks for the advice. I will definitely buy used parts.

Just upgraded tires to 17x8 and added LSD. questions:

Where can I find cheap hawk blues? I am looking at $157 for the front, too much.
Tie bars: Are you talking lower front tie bars?
I think Flywheel, clutch and shorter shifter will not add that much in terms of performance, would you agree? I still have them at the bottom of my list.

Chipping is not enough, I wanted a bigger turbo to get up to 300whp (the max without doing heavy improvements such as rods, injectores, fuel pump. I wanted to do only exhaust, chip and intercooler). Any suggestions here?

The setup you listed is not good enough. Assuming you have plenty of track experience as you have already stated, it would be cheaper to look at a well sorted car to begin with. I actually happen to know of one for sale that is setup for just that. Which side of the country are you on?

I enjoy the process of upgrading it, bit by bit, so I´d be interested in the used parts for MKIV, let me know, I am in NorCal.

On the super cheap:
Weight: Gut the car
Suspension: Get rid of every rubber bushing possible. Get PSS9's
Power: Chip it

thanks.
I just saw your car, congrats, it looks awesome.
I agree with comment about saving weight.
Question: 1) why change all bushings? I saw you did it to your car. would it add on handling, or it´d just improve reliability?

[Mmack]

Be careful with lowering if you don't have spindles that correct the geometry. Lowering the car 2" will really detract from the handling. At that height, any suspension compression will actually make the tire gain positive camber (the opposite of what you want). The H2Sport spindles correct this by relocating the ball joint so the LCAs are parallel to the ground when the car is somewhat lowered. This restores the geometry so the car has a "normal" camber curve as the wheel travels upwards (compresses). It gains negative camber as the good lord intended.

Your best options for handling are to either not lower the front at all, or get H2Sport spindles so you can lower it without compromise. (Mine went with the car when I sold it.)

I'll dig out the camber plates if you're interested. Shoot me a PM with your email address. Sounds like you're leaning toward PSS9s, but lemme know if interested in the Ground Control coilovers.

Mmack

[mgyip]

QUestion: what pads to use on track? Hawks are more expensive than EBCs.

Hawk Blue is a good all-around track pad. if you need more, their new DTC line seems to be good - unfortunately for me, they don't make them for the antique VWs so I'm stuck with HT-10s.

[2 doors]

Sounds like you're leaning toward PSS9s, but lemme know if interested in the Ground Control coilovers.

Mmack

I sent you a PM on this subject.

[TyrolSport]

17x8 or 8.5 ET35 with 255/40-17 will give you more grip than 225s, and will fit without rubbing.

[rex_racer]

On the track, where you are pushing the car at 100% for extended time intervals, I'd be leery of running the engine at 300whp. Being able to do so on the street is very different from doing so at the track.

[TyrolSport]

I ran my 1.8T GTI at 300whp on tracks all over the Northeast without issue. It requires a time and money, but it can be done.

[zooyork155]

I believe rex_racer was referring to running 300whp without upgrading internals.

[T-redmk2ABA]

http://www.kermatdi.com/servlet/-str...-Street/Detail

There is your suspension right there , you don't need go buy new spindles cause you won't lower the car and I LOVE my real street kit ... better hurry they don't have many left shine stopped making the real street kit ( race is to extreme for the street) they don't have many left.

It's a fixed suspension no adjusting its all set and you can live with it everyday , shine also has really good camber plates and bearings to remove the rubber in the lca's and the rear beam . Also when you put in the "big" rear shine bar Dick suggests removing the front bar altogether ( Idk about mark4 but on 2 and 3 he does )

[3lfk1ng]

thanks.
I just saw your car, congrats, it looks awesome.
I agree with comment about saving weight.
Question: 1) why change all bushings? I saw you did it to your car. would it add on handling, or it´d just improve reliability?

-No problem,
-Thank you very much.
-The harder/solid bushings improve responsiveness and handling. Also, the rubber wears quickly so I would imagine it helps with reliability to a certain degree.

[enginerd]

I second the spindles. One of the best mods you can do to fix the bad front end geometry on the MKIV's.

Spindles, camber plates, spherical metal bearings, clutch, LSD, coilovers - with very stiff springs, hawk blues, RSB, chip it then go play. Add the big power when you get it all sorted out.

BTW the above car is awful to drive on the street and your wife wont want to drive it anymore.

[3lfk1ng]

Actually my car is pretty comfortable on the street thanks to the PSS9s. It's no Merceded by all means but it rides comfortably.

Thank you for voicing your opinion on how my car feels on the road when you have never been in it though.

[mgyip]

I think you're getting a bit defensive - what enginerd is saying is a fact of life for a car with super-stiff springs and metal bushings. Even with PSS9 coilovers (which are overpowered by springs greater than 400#), the resultant ride will be worse than my F350. Ultimately, if you find the ride is comfortable on the street, you either have an iron-butt from riding old Harleys OR your car is way too soft for the track.

[3lfk1ng]

My apologies, I didn't mean for it to sound like I was being defensive, what I should say is that I have never been in a track purpose car that is nearly as comfortable as mine.

In fact my good buddy Ivan was really impressed with how comfortable it was on the highway driving about 50miles to a car show. I have no back issues to speak of when driving over a period of 4-6 hours (Big Bear, Las Vegas). The same cannot be said when I drive two hours in my wifes bone stock Audi A3 2.0t (to Huntington Beach). I will admit that part of the comfort is due to the ergo of the Recaro seats (in my GTI, the A3 has fancy perforated "S-Line" Alcantara).

Anyway, I have been in track built Miata, BMW, S13 and they all drive super stiff and horribly uncomfortable to drive on the street with. There is a lot of bouncing around and hard bangs when driving on public streets. My GTI is waaay more comfortable but still track built. Like I said, it is no Mercedes but it is entirely tolerable.

Setting the dampening to 1 on public streets.
Setting the dampening to 10 in the rear and 4-6 up front is for track.

The difference is noticeable in ride comfort and handling .

I did use to ride motorcycles. My last bike was in 2009, it was Suzuki DR650.

The car is definitely not too soft for track, it handled really well this weekend up at Buttonwillow, I should have some footage available later this week.

Sacrifices are going to have to be made (big or small) if his goal is to keep up with EVO's and STI's.

[3lfk1ng]

Here is the footage I mentioned I would post


Hope you guy's enjoy it more than the MK4 forums did

[1stgen]

A few helpful hints...change your seating position, get closer to the wheel, hands at 10 and 2 and STOP shuffling your hands. Smooth is faster...your not very smooth and those tires are **** even though you are over cooking it on entry and exit. Slow down and get smoother

[mgyip]

Not a shuffle-steer proponent, eh? That's a big "personal preference" issue - if the OP likes it, leave it alone.

The seating position looks a big far back but the OP also looks to have his legs jammed under the steering wheel. Instead of moving the seat forward, try moving the seat BACKWARDS but bringing the seatback more upright.

As already noted - SMOOTHNESS is your friend. It every turn, I see a minimal amount of initial steering input and then HUGE steering input to keep the car on the pavement. This means that you aren't reading the turns and looking ahead - at the turn entry, look for the apex and on to the turn exit. The turn should be one smooth arc, not a 20 degree turn followed by a 45 degree turn/correction. In other words, once you enter a turn, the steering wheel shouldn't have to be moved again until you reach the turn exit.

1stgen is correct - slow down and build the basic skills. Once you have that, you'll get faster because you won't be fighting the car. Hold off on spending money to make the car faster - those mods will only serve to mask more fundamental car control issues that need to be addressed and resolved.

3lfk1ng - Please don't take this as an insult - you posted the video and we watched it. Some of us have a fair amount of on-track experience and some of us are crazy enough to actually sit in the passenger seat at these events. This is the same debrief that you've probably received at other events, just on-line with a boat-load of people watching your video.

What's a bit disconcerting is that while you can make your way around the track, whomever signed you off for Solo let you develop some very bad habits that can cause you great sadness in the future. Fix those habits and you'll be surprised at how few mods it takes to smoke an Evo or an STi with a "lesser" car.

[3lfk1ng]

Thank you guys for watching the video and taking the time to help me out, it is nice to finally find people on this forum who are helpful and informative when it comes to Motorsports (and perhaps other things?).

@1stgen
Thank you for your advice, it is greatly appreciated. I will be sure to find a better seating position this weekend, one that I can drive with on the streets. While I don't drive recklessly on public roads, I can certainly practice better driving habits.
Yeah I am definitely going to have to learn how to keep my hands in the correct position, it's a really bad habit. In my earlier sessions I was doing lap after lap by steering mostly with just one hand (like a busdriver) and leaving my other hand on the shift knob. I took my friend for a session who has 5 years of track experience with his E30 and he told me the same exact thing. In fact, he let me borrow the gloves I was wearing and told me to keep them on the steering wheel and avoid leaving my hand on the shifter. I feel that I was at least able to follow his advise but there is definitely room for improvement, a LOT of room for improvement.

Yeah, the tires were being borrowed from another friend, they were Hankook Ventus V12 EVO's and they had a really soft sidewall. Like a noob I was pushing them past their limits and expecting more responsiveness. Although I felt like I was going where I wanted, watching the all the squealing tells a different story.

My new wheels will be here within a month and I plan to put some 245/40r17 Dunlop Z1 Star specs on them. Hopefully they will drive as smooth as aircooled56's .:R32 or maybe I just need to slow the eff down and find better driving lines.

EDIT: Worth noting: I was only able to get -1.5 camber up front when we were aiming for -2. The stock tie rods were too short, anyone mind sharing their alignment setup? (Here's mine)

@mgyip
Oh no problem, I'm not offended in the slightest. I know that I am a complete noob at this, so any and all advice is greatly appreciated. I have never done any event(s) before, not even autocross, this was my very first. I knew that I would make mistakes which is why I recorded the cockpit. I wanted to be able to watch my bad habits afterwards and learn from them before the next event. In fact, the whole reason that I picked Buttonwillow was so that I could avoid walls.

As for the shuffling, I honestly don't think I can completely eliminate it on turns like the cotton corners (can I?) but I will certainly do my best to reduce it and perhaps find a way to execute my turns in a smoother more fluid motion. Maybe by going wider it could keep my hands at 10 and 2, I won't really know until next time.

No one really signed us off for SOLO, they held a driving school on Saturday where we followed some basic rules behind an without any instructor and then once we finished that were were all bumped into the SOLO class for Sunday. I learned more by taking experienced drivers for ride-alongs that were willing to instruct me than I did on my very own.

__________________________________________________ ____

Thanks again for all your help. Sorry to jack the thread.

[mgyip]

I'm surprised that the event organizers moved everyone to SOLO for the 2nd day of the event. Historically, the 2nd day of a 2-day event is when all the bad stuff happens because the newbies have enough knowledge to get into trouble but not enough knowledge to save themselves. I'd suggest finding an organization that doesn't promote drivers as a participation reward but rather on merit. There are some participants who have attended dozens of events who will never make it past Novice - those are the students that we call OSB - Other Sports Beckon.

As you get more involved, you'll find that your bad habits will eventually go away - work on breaking those habits on the street so that when you're at the track, you'll be able to focus on driving. That said, many of my on-street habits (driving with one hand and napping) go away when I'm on-track because I don't see track driving as transportation but rather as a sport (per se).

[enginerd]

Actually my car is pretty comfortable on the street thanks to the PSS9s. It's no Merceded by all means but it rides comfortably.

Thank you for voicing your opinion on how my car feels on the road when you have never been in it though.

by above, I meant the car I just described above not your car.

a true purpose built track car is not going to be a nice street car. A fat pig MKIV needs 600+ lb springs and a monster sway bar to keep from rolling like a mini van. Unfortunately with the macpherson strut setup you need to keep it from leaning so you don't lose all your camber the only way to prevent the leaning is massive springs.

You can get away with softer springs if you run alot of static negative camber, and the spindles are great even if you do not lower the car. The OE suspesionis designed to understeer when at the limit. Even a stock ride height has a poor camber curve that makes the front end plow with any body roll. I am running the spindles with a "high" and very stiff front end. Combined with a splitter the front end is glued to the track. The rear end is another story, but there is not much to do about a twist beam noodle.

[chois]

Hi all,

I am buying a MK4 GTi for trackday use, and I want to upgrade it to a very competitive level,close to STi/Evo

Huh? Competitive level? Are you doing time trials or track days. Track days are not competitive - though they are a whole lot of fun.

1) this is not my first trackday car, dont be worried about me getting seat time

My first thought is turn down the ego. The reality is that every single one of us in this forum will likely gain more speed if we get more track time - not simply due to improving car control, testing alternate lines or other driving tasks, but fine tuning the setup of the car. Big things like anti roll bar and shock adjustment settings or spring rates and weight distribution. Little things like tire pressure at each corner, alignment (also at each corner of the car), brake bias, brake pads, tire choice.

2) I know this is a long term project, and should be done bit by bit. But I am leaving the country shortly, and need to buy all the equipments and parts for this project NOW.

Getting the most out of a car takes a more measured approach than buying a pile of cool parts. While I don't understand why you need to buy all the parts now, but I would expect that what you end up with if you were to stick with this project would be pretty different from what you or any of us suggest at this moment. As you make upgrades, learn how they affect the car, and learn how they impact your driving the next thing that you want to do to the car will likely evolve.

3) I have a good budget for it, but will spend considering the "performance added per dollar spent".

This does not matter a ton. You will have the option to spend more money or taking more time to make/modify things yourself and search for deals. We can't help you with that choice.

- is this setup good enough?

That can't definitively be answered, but probably not. Too many flaws in the VW chassis, which has a huge impact on lap times - especially over the course of a long run.

- what would you add/remove (considering "performance added per dollar spent")?
1) Brakes
a) Upgrade front to 12.3" and rear to 10.1" slotted rotors,
b) track pads (EBC yellowstuff or Hawk HPPlus),
c) Motul brake fluid
d) brake lines
Question: I am not planning to change calipers and carriers. Do I need it, and is it worth it?

2) Suspension
a) Bilstein PSS9 (I need something adjustable, to run street as well - wife is going to drive)
b) Rear anti-sway bar (neuspeed?)

3) Tires/wheels
a) 225/45-17 Hankook RS3 tires (slicks wear out too quickly, much more expensive to maintain)
b) 17x8 wheels (anything cheap. ideas?)

4) Engine/power/transmission
a) 3" Eurojet cat-back Exhaust (cheapest one I found)
b) Bigger turbo + remapping (which one???). looking for 300whp max
c) TIP
d) SMIC upgrade
e) LSD (Wavetrac)

Don't bother with bigger brakes. Go with more aggressive pads that you swap out at the track (something like Hawk DTC70). Also take the time to fab up effective brake cool ducts. You may also find benefits of going to a manual brake bias adjustment, but would need to remove ABS to do that.

The suspension will be your weakest point. If it needs to be good for the street, it can't be good for the track and vice versa. The best you can do is improve some of the basic short comings by going with the H2Sport spindles or making some ball joint spacers, installing camber plates and adding roll stiffness in the rear. I would consider saving money over the PSS9 stuff and going with coilover sleeves and re-valved Koni or Bilstein dampers. This gives you more freedom to find a spring rate combination that suits the level of compromise that you are willing to accept in both environments.

Race tires are not as expensive as you think - if you set the suspension up properly and only use them at the track. They will also make the single largest improvement in laptimes of anything else mentioned here. However I agree with choosing a streetish tire, provided it can stand up to the high heat you will be throwing at it. I don't know these options well enough to make a recommendation.

Of all the engine transmission list, the differential is the most benefit. The wavetrac is probably as good a street diff as any. To get appreciably better stuff would require multiples more $$. The added weight and heat of big turbo modifications will provide a lot more down time at the track, but of course over time you can work that out as you break and fix things. However - I can say that a very high power fwd track day car sounds like it will not really be that fun (of course that is a bias of mine)

- where to buy it cheap?

Buy it second hand or spend more money to get it now. You won't find big enough deals on new parts relative to the overall cost of an extensive build to make a difference.

My last recommendation is to give a lot of consideration to the safety systems that you plan to include in the car and on yourself. Of course this is hard to do right in a dual purpose car, but give it thought and ask questions to folks with race car experience. There is a massive amount of expertise out there, and the folks that have it were happy to share with me when I was building my car.

thank you very much

Good luck with the project. Let us know how it works out.