Custom Exhaust : It Begins

[Draxus]

The downpipes / headers are staying stock for now.

Next project is making some headers. This summer I will probably start on that.

[Draxus]

So its on...

We just have it turned down right after the rear diff right now. Cattless to single Burns muffler.

On the Burns Muffler... I took it apart to get a feel for what I paid. I am never going to buy one again. Not fantastic inside.

Anyway.

It is so loud that it clips my camera mic. I am needing another muffler. It sounds great, except for the level of it. On the way back from SCCA (where it sounded aweeeesome on the track), we stopped and got some ear plugs.

It is about as street legal as beating your wife with a golf club at The Olive Garden.

1-2k RPM is ok.
2-3k RPM DANGER ZONE. (drone for days)
3k+ Formula 1 car.

It's sick if your on it but it is just a pain around town. Really took a lot of fun out of the car. But, that was expected as... its a damn single muffler.

Sound:

At idle: V8 mustang

Around town: Uuuh, T-rex?

On it: So, imagine Chewbacka just got back to his home to find it burned down and his wife and kids hung from the tree in his front yard and then him falling to the ground and letting out a blood chilling yell to the gods.

.....yeaaaaa.


Vibrant Muffler vs Magnaflow

What size exhaust tip? 4" or 4.5"

Best place to get said tip?

Thanks.

[simple_man]

Car: MKV R32 T STAGE III
Exhaust few days back: 3" downpipe > 2x 100 cell cat > 3.5" pipe > stright tru maffler > 3.5" pipe > stright tru maffler

Result: same as your mate. Hate it! 1500-3000 = major drone, 3000rpm onwards F1 on boost.

Coming back to the shop to fit spiral muffler + replase one stright thru with baffled muffler.

[CaptainQualude]

Vibrant Muffler vs Magnaflow

What about a Borla Turbo Muffler?

[nkgneto]

I'd be interested to see the Vibrant muffler. It is one of my options as soon as my high flows go on.

[Draxus]

What about a Borla Turbo Muffler?

What is good about them?

[R32R1]

Loving the descriptions lol

[BOUDAH]

So its on...


It is about as street legal as beating your wife with a golf club at The Olive Garden.

LMFAO.....

[CaptainQualude]

What is good about them?

Good flow with reasonable sound control.

[Det. John Kimble]

Loving the descriptions lol

I second that

[rex_racer]

So its on...

We just have it turned down right after the rear diff right now. Cattless to single Burns muffler.

On the Burns Muffler... I took it apart to get a feel for what I paid. I am never going to buy one again. Not fantastic inside.

The Burns mufflers are only meant to take off a few db. The primary goal of the Burn's mufflers is to have a re packable muffler that is super lightweight.

The turns downs, especially being so close the rear axle are probably contributing greatly to the drone. You should try directing the exhaust out the back before you swap out mufflers.

If you want to record it, try rubber banding a cotton ball in front of the mic when recording. That will greatly help to reduce chatter noise.

[Draxus]

Here is a video taken from about 150 yards back from my Nexus One cellphone.

http://vimeo.com/22267636

Never left second gear.

[Draxus]

The Burns mufflers are only meant to take off a few db. The primary goal of the Burn's mufflers is to have a re packable muffler that is super lightweight.

The turns downs, especially being so close the rear axle are probably contributing greatly to the drone. You should try directing the exhaust out the back before you swap out mufflers.

If you want to record it, try rubber banding a cotton ball in front of the mic when recording. That will greatly help to reduce chatter noise.

That is a good point on the drone.

Also, I knew it wasn't going to take it down a lot volume wise. I was commenting on the build quality. Looks great on the outside, but the inside is fairly meh. Not bad, or worth complaining about to Burns. But, not worth almost $300.

[Av.]

Here is a video taken from about 150 yards back from my Nexus One cellphone.

http://vimeo.com/22267636

Never left second gear.

Nice vid! But the fog or whatever ruined the video

[Draxus]

I am so scared of picking the wrong muffler and ****ing the sound up.

Arg.

[Cortexiphan]

Magnaflow?

[Sutt]

Why not pack the muffler with more material?

[EMANNvr6]

I was laughing in my lab class reading those descriptions haha

Must sound insane !

[huichox4]

I am so scared of picking the wrong muffler and ****ing the sound up.

Arg.

get a cherry bomb ............................ I might actually do that because my car is obnoxiously loud and I am cheap

[Draxus]

Muffler Question:

Example muffler as a Borla Turbo.

How would the sound differ from a oval and round of the same length?

I would assume that the oval would be quieter due to damping mass, yet how would the oval size effect the sound?

Anyone know?

[Draxus]

I am thinking about throwing some cats into it to pick up some low-rpm torque and tone down the frappy rasp-ness.

Then maybe another burns muffler out the back...

I have learned how to drive it so it isn't that bad anymore. Still balls loud, but man does it sound good at WOT.

[huichox4]

I am thinking about throwing some cats into it to pick up some low-rpm torque and tone down the frappy rasp-ness.

Then maybe another burns muffler out the back...

I have learned how to drive it so it isn't that bad anymore. Still balls loud, but man does it sound good at WOT.

Cats will help quiet it down

[spitfire481]

no tube style muffler i ever had was quiet enough. i had to add a oval cased muffler to make it street-able. dual 2" down pipe to 3" no cat into a magnaflow oval case muffler is just right for me. mine is a 2.8 but it wont be much different. the turndown makes a ton of drone. i had mine under the car about 12" from the bumper and it was horrible. moved the turndown to the very edge of the bumper and just that made a huge difference.

[Draxus]

no tube style muffler i ever had was quiet enough. i had to add a oval cased muffler to make it street-able. dual 2" down pipe to 3" no cat into a magnaflow oval case muffler is just right for me. mine is a 2.8 but it wont be much different. the turndown makes a ton of drone. i had mine under the car about 12" from the bumper and it was horrible. moved the turndown to the very edge of the bumper and just that made a huge difference.

I am thinking of adding another burns oval and putting it out the back. That will take care of the drone I bet.

[Draxus]

Just ordered cats and another v-band.

Cats came to $140 with free shipping.

[alvint@borla]

Muffler Question:

Example muffler as a Borla Turbo.

How would the sound differ from a oval and round of the same length?

I would assume that the oval would be quieter due to damping mass, yet how would the oval size effect the sound?

Anyone know?

I might know...
Larger mufflers have more packing material and are generally quieter than a same length round muffler sharing identical muffler core diameters.

[Draxus]

I might know...
Larger mufflers have more packing material and are generally quieter than a same length round muffler sharing identical muffler core diameters.

Yes, there will be more of a dB drop, but I was curious about a tone change.

[alvint@borla]

Yes, there will be more of a dB drop, but I was curious about a tone change.

Assuming an identical muffler core design, expect minimal frequency change due to similar exhaust gas velocities.
In general, expect a drop in sound pressure level (less dB) when changing an oval muffler to a round muffler of the same design.

Pipe diameter changes affect exhaust gas velocities that can change the exhaust note frequency.

[Draxus]

Two cats came today:

[Cspence]

looked through 4 pages only to be dissapointed that there was no video...

[Draxus]

Cats are in. Sounds amazing. Debating just sticking with the single resonator and piping it out the back. I'll try and get a video. No rasp. All deep rawr.

[nkgneto]

C'mon this thread is useless with out pics! LOL



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- Sent from my iPhone using Tapatalk

[Draxus]

Bah! Fiiiiiine. I'll get some. Haha

[DannyLo]

Wow that really is loud in that clip!

I guess my turbo helps that much. I have no resonators, and only the 9" like i mentioned earlier and it's very civil when I'm off the throttle. On the throttle, with my external wastegate dump, even with 10 mufflers all bets are off

[simple_man]

Car: MKV R32 T STAGE III
Exhaust few days back: 3" downpipe > 2x 100 cell cat > 3.5" pipe > straight tru muffler > 3.5" pipe > straight tru muffler

Result: same as your mate. Hate it! 1500-3000 = major drone, 3000rpm onwards F1 on boost.

Coming back to the shop to fit spiral muffler + replace one straight thru with baffled muffler.

My issue is that 3.5 inch with straight thru mufflers for the flow is too loud and there is a major drone at 2300RPM.

So, experiment 1:
I had two straight thru mufflers + 20 inches of spiral (think moroso).



Now added third straight thru muffler after the CAT's and reduced spiral length to 12 inch:



Result is slight reduction in drone and it's shift to lower RPM, now sit at 2100RPM (left overs). So, as theory tells us, absorption mufflers (high flow type commonly used) do not do much at low frequencies. They suppress 300/600 Hz upwards. Nothing down low where we need it most, about 100Hz. So use of those to help the drone is noneffective. One needs baffled type muffler of CORSA type with branch resonator technology. Those will work much better below 300Hz.

So, we still have some minor drone that needs to be addressed and a very high flow system that sounds really nice and deep 4000RPM upwards.