Very good info. 1.75 is a great 60’ for these cars. Ill stick to that technique. Don’t want to chance burning up the transmission.
yeah an X makes more sense. the goal is to allow the streams to mix when they want to, not force them to
in all likelyhood it is the fuel pump priming so the car starts sooner
Good info B. It is surprising the high percentage of expensive aftermarket exhausts that have poor design. It is like the guys designing them have no idea what they are doing.
Exactly. The single pipe idea is terrible. You want to create more low pressure transitions not build a low then high pressure siuation like with the single pipe
Yep. It is really amazing how many bad exhausts are out there.
Mental note:
Do not buy ten thousand dollar headers from the guy who thinks that dumping the exhaust from both sides of the NA v10 engine into a huge, extended collector is a fantastic idea
I would say definitely don’t give that guy money.
I have a miller exhaust, and mine does the same thing… very loud exhaust note at idle for the first minute or so, then it disappears as soon as the idle dips back to normal. Honestly I never gave it much though, just thought it sounded awesome on my way out the driveway, and left it at that 
^ Dammit, that’s the last time I post with my phone
On my friends S6 with custom exhaust with just a couple magnaflow mufflers, it sounds like a race car on cold starts. It’s obnoxious and awesome.
Hahaha… nice!
[quote=“v8a6,post:4,topic:6765”]
Speaking of that S8, on an NA car does it make sense to merge the exhaust from the two sides into one giant collector, and then split them up again?
Yeah that’s a foolish set up at a glance. Probably some acoustic boosting effect, and building heat, but not building any power. Anywhere exhaust gases just merge, without proper consideration for flow (more specifically each cylinder fire/pulse), will result in wasted power, and heat build up. I’m guessing that’s just a wide-open obnoxiously loud exhaust (?)
Yeah that’s a foolish set up at a glance. Probably some acoustic boosting effect, and building heat, but not building any power. Anywhere exhaust gases just merge, without proper consideration for flow (more specifically each cylinder fire/pulse), will result in wasted power, and heat build up. I’m guessing that’s just a wide-open obnoxiously loud exhaust (?)
For example, an X-pipe, as seen on a C5 V8 Audi exhaust, comes together but immediately splits apart for a reason. The goal is not to actually merge the two sides of the exhaust, but rather to provide an alternate path of flow for each side of the exhaust. Allowing the two manifolds to share a common space at the middle of the x allows exhaust to flow down the path of least resistance at any given time. As the cylinders fire/pulse on each side of the V8, each pulse has a choice of which muffler to exit. It really shines at higher rpm as the X-pipe merges the pulses into two seemingly uniform streams.
http://audirevolution.net/addons/albums/images/592807793.jpg
On an interesting side note, the X-pipe set up builds a bit of power, and smooths out the American muscle growl/sound of the V8.
For more of the muscle car sound, an H-pipe is used, as seen near the center of the photo in v8a6’s picture in Reply #1. The H-pipe allows for gas to expand into the H-pipe section during pulses. Both sides of the exhaust push back and forth through this common area, again allowing overall flow/exit of exhaust to be smoother.
I believe that’s called “brake boosting”. Really not good for transmission!
And I musta missed that part about the H-pipe being a solid piece on the V10 exhaust. Interesting that there would be no crossover whatsoever…
Yes thats what I thought as well. It explains why the exhaust sounds the way it did before the X.
As far as the Braking thing Brake boosting is really only on Turbo cars, the more Ive messed with it 0-60 wise it seems like I get better time flooring off idle and also shifting before the redline (if its in sport mode takes forever to shift when floored on its own almost like its hitting the rev limiter,
you might find shifting 200-300 RPM before the rev limiter is optimal for curve reasons. The low revving NA cars tend to fall off hard up top.
I used to shift my B7 S4 at 6800 RPMs or so. Maybe 6600.
First I would wind right out, but then on it was a bit before redline. The car was flat above 6500-6600 really.
I agree it drops off pretty hard. Even with the 93 APR tune