What's the View Here on Catless Downpipes/Cat Deletes?

[jepva]

TO those who think HFCs or test pipes do not add to performance, you are misinformed. It does depend on the car and how restrictive the stock cats were, but most late model cars always experience a gain in exhaust flow, and these performance improvements are heavily documented.

Also, it is not just for FI cars. On the G37, HFCs are dyno proven as one of the single most gaining modifications with about 20whp improvements over stock. There are two of them, so that's one of the reasons.

Contrary to popular belief, most also see improvements in MPGs.

That being said, of course it will let more CO2 out of the car. However, the % of people doing this is so small, I doubt there is any significant scientific detriment on a large scale, especially not enough to offset the yearly decrease in nationwide emissions with the advent of more efficient and less polluting cars taking to the roads each day. I'm not saying it's OK, just that it's not this horrid thing a lot of people may make it out to be.

What you all should be worried about is CHINA. Talk about pollution.

[rs4-380]

I have no cat on my rabbit. I *may* drive it several hundred miles a year. Berate me if you may, my header setup somewhat precludes it.

[SVTDanny]

More power, faster spool, popping, gurgling, and turbo jet noises through the exhaust..... what's not to love?

I might be alone on this one, but I love the smell of a catless exhaust, especially after decel through the gears.

My wife's Sonic will see 10x the miles that the Mustang will in a year, so... eh.

[Toaster29]

I have a catless setup on the GT-R. Sue me. The benefits far outweigh the negatives and the car doesn't get driven that much anyway.

I have a HFC on the Acura, which sees 15k+ miles a year. The headers came with a test pipe, and I had an aftermarket HFC welded in. Toned the noise down some and the car is happy with no CELs or anything.

[weakshht]

I have a catless DP on my GTI.

But i live in Alberta, ****ing up the environment is what we do..

[jamerican1]

Inb4GermaniuM... Lol

[Mintyy]

This owner has yet to do a cat delete.

[S0RRY]

What you all should be worried about is CHINA. Talk about pollution.

welp, since china's polluting, we might as well just give up! Love reading some people's justifications for doing selfish things.

[vasillalov]

That being said, of course it will let more CO2 out of the car. :

Actually, the CO2 emissions remain the same. It is the emissions of particulate matter, un-burnt hydrocarbons. nitrogen oxide and sulphur that does not get suppressed by removing the catalytic converters.

[cockerpunk]

welp, since china's polluting, we might as well just give up! Love reading some people's justifications for doing selfish things.

you know, i understand the science behind climate change, i understand the effects of man made carbon gasses on the radiation absorption of the atmosphere, i do. i vote democrat, i even freaking recycle.

but really, there are battles to fight, and there are battles that arnt worth fighting. and you know, im not going to feel guilty for by passing the cat on my classic car. sorry.

its just not an issue. really.

[patrickvr6]

Yeah... catalytic convertors usually don't "go wrong."

Cats fail all the time and they are a big reason why a good number of late model cars are scrapped or traded in for something new.

I just spent $1400 and 12 hours of my time replacing the cats on my 325i because I have to pass emissions with it. If I didn't get tested I would bought straight headers and not worried about it.

welp, since china's polluting, we might as well just give up! Love reading some people's justifications for doing selfish things.

Read this and then get all sanctimonious about someone choosing not to run cats.

http://www.gizmag.com/shipping-pollution/11526/

[S0RRY]

you know, i understand the science behind climate change, i understand the effects of man made carbon gasses on the radiation absorption of the atmosphere, i do. i vote democrat, i even freaking recycle.

but really, there are battles to fight, and there are battles that arnt worth fighting. and you know, im not going to feel guilty for by passing the cat on my classic car. sorry.

its just not an issue. really.

I was more mocking his justification than the act itself. I personally don't care if you run cats or not, but nothing annoys me more than logical fallacies.

[eunos94]

Pre-cats can be very restrictive and only provide benafits for 30 seconds of every day... so I'll cave and say you aren't a total douche for removing those but removing the main cats is still a douche move. I went with 3" high flow cats on a 1.8 liter forced induction engine. Massive over kill but they flow fantastically well and my turbo spools up PLENTY fast thank you very much. All while still being kind to the planet we live on.

[ncbrock]

Screw the environment. Do it for the fire!

im with this guy, it was a a given to remove the cat with webers or else it would have gotten ruined anyways

[elmer fud]

if you have a reason to remove it.... IE....diesel, carbs, or FI that is running rich for performance reasons, then yes, if just because you want to add 3 hp. n0o0o0o0o! cats on most modern cars almost have a immeasurable effect on power and will usually get you in huge trouble if caught with out them.

in the last few years I have owned 3 cars with out them, a carbed rx7 that shoots 3 foot flames (tried one killed it in 3 days), a tuned tdi , running rich enough to kill it so I pulled it before it could, and a car that didint come with one stock. other then that the have or had cats. my miata's cat is worn out, and I plan on upgrading the cat, but the CAR WILL HAVE ONE.

[Ungarisch]

I purchased a high flow cats / down pipe for my WRX and it made the car smell like a 70s era soviet car, made me wonder why I bothered with the cat. A grandma took it out before it had its first SMOG inspection (required on the 4th year from new in CA), so I don't know if it would have even passed, just saying, high flow might just mean it ain't doing shizz besides making you feel like a responsible person.

[n0rdicalex.]

if it's a true race car, then by all means go catless. but even then, i believe Grand Am series cars have cats - ST and GS, i believe.

but, a universal Magnaflow High-Flow cat cost me $94 shipped and another $20 to have installed at some local exhaust shop. i didn't have to worry about CEL's, spacing out O2's, or anything else. it free'd up some power and increased flow, and wasn't all that bad for the environment. i also live in indiana, and even though we don't have emissions testing, it's just something that makes sense.

plus, i like breathing fresh air. don't want a cat? then don't complain about smog or bad air quality.

[Nateblizzy]

"Took the restrictor plate off to give the Red Dragon a little more juice. But it's not exactly street legal, so keep it on the down low."

I bought my car catless, but just a cat would get blown out if I did put one on. It backfires like crazy, and smells like donkey farts. On the other hand, it only gets driven about 6-8,000 miles per year so I don't feel so bad. My car failed emissions the first time, but it wasn't due to being catless. It failed because I was throwing a CEL for some unrelated sensor.

[Internal Combustion]

pre-cat cats- doubt they do much at all besides during warm up. these are restrictive and I would remove them from any performance minded car

cat deletes- I removed the Cat on my 98 Jeep grand cherokee 5.9 after running a 3" carsound. I picked up about 7 rwhp, from 297 to 304 rwhp. I didn't really like the stink though. I wouldn't do it again on a DD.

[302W]

On an older, more aggressive car I don't run em. On a daily that is stock or mild I prefer to have cats though.

[Horror Business]

When I had my MKIV I ran a 3 inch catless downpipe on an entirely stock 1.8t except for 007 forge DV and a short ram intake for a short time..

Boost increased about 2psi, I felt a loss of low end torque but more power on the highway. Although I never tried it with a cat, word was back then from most people who have done dynos that the stock cat was allready free flowing and made no difference except for very high horsepower cars.

[DrFrisker]

start a poll next time farg
precats in the 1zz motors like getting sucked into to the cylinders

[Run L1ke H3LL]

It was cheaper not to buy an aftermarket exhaust without one. Do I feel bad sometimes? Sure. Do I lose sleep? No.

Why? Because I would bet a whole lot that half the righteous folk in this dumbass thread don't give a hoot about the environment. I bet you smoke, litter and don't even recycle. So unless you're effin Captain Planet then piss off.

[cheap sunglasses]

If you're going to play the environmental debate on this, don't think of in terms climate change. Think about it in terms of local air quality, where catalyzed automobile emissions have made real improvements in people's health and quality of life over the last decades, even yours. The image of 1970s-era Los Angeles, or present-day Beijing should give you an idea how modern emissions systems and standards improve air quality.

So think about it when you're doing a cost/benefit analysis of whether or not you should remove the cats from your car.

[jepva]

I was more mocking his justification than the act itself. I personally don't care if you run cats or not, but nothing annoys me more than logical fallacies.

I never said it was an excuse (maybe you should read), but if you want to bark up the pollution tree, I'm just saying, going after the few car guys who use HFCs or test pipes is probably a big waste of your time.

[S0RRY]

I never said it was an excuse (maybe you should read), but if you want to bark up the pollution tree, I'm just saying, going after the few car guys who use HFCs or test pipes is probably a big waste of your time.

lol, you just used the same fallacy again. If everyone thought like you no one would ever do anything because someone was always doing more, or faster, or worse, or better, or whatever. It's a weak mindset.

[jepva]

lol, you just used the same fallacy again. If everyone thought like you no one would ever do anything because someone was always doing more, or faster, or worse, or better, or whatever. It's a weak mindset.

You just don't get it. Take your logical fallacy crap back to Phil 101. You're probably one of those people that doesn't buy gas on X day to get prices to go down.

[Buckeye(OH)]

I deleted my second cat. If I were to do a downpipe, which I am not, I would spend the extra change on one that was catted.

[vwlarry]

I never imagined that such practices still existed! Years ago, in the seventies, when cats were still new and totally unreliable, we VW guys just bought what we called a "test pipe" that bolted into the gap where the catalytic converter used to be. End of problem. It's not so simple now, with all the engine management/feedback/electronics involved that were not there back then.

Jeez, they still MAKE the things! I had no idea!

[AZGolf]

Really, with the advent of reasonably priced, high performance, high flow cats, there's no reason not to run them

This mirrors my thoughts.

[Air-over-water]

I still have the cat on my project car, but it is hollow.
I was driving a few years ago and it all broke apart on its own, clogged the exhaust pipe at the first 90* bend, So I cut the pipe at the bend and let all the pieces blow out the back, then welded up some new pipe and called it a day.
Easy fix for a car that is not driven on the street.

[SnowGTI2003]

I run a high flow cat on my STi. The downpipe was about $200 more than a catless one so it was a tough call. I'm not a huge fan of the catless stink so I went with a catted downpipe.

[l88m22vette]

My bolt-on DP has one, and once I get the engine built I will still run one (3" race cat), IL has emissions checks every year, and while I have my ECU coded out for that stuff I don't want to chance stinking up the emissions test center and raise suspicion. My TT is and will be a daily, and I'm sure the minimal power gain won't be outweighed by worrying about the smell and chances of getting into trouble.

That said, uncatalyzed exhaust smells awesome, and the popping/gurgling/chances of flamethrowing is certainly appealing. I suppose I could pick up a cat delete section for summer fun (though a loud blue coupe shooting flames won't be cop-friendly fo sho )

[BassNotes]

Delete the cat. It's a big atmosphere, tree huggers.

Dump your used motor oil in the storm drain. It's a big ocean (or river or lake). Lift up the grate and drop the filter in, too. Pretend it's Ed Begley Jr.'s face you're dropping it on.

Leave your used coolant out for the neighborhood kitties.

[AggvGtivr6]

Increased MPG's > whatever comes out the back from not running a cat.