Got to talking to a guy at a local car meet a week or so ago... I think he's on here somewhere, but I can't remember what he said his username was... anyway. We were talking and he had claimed he believed that the single exit exhausts were showing more power gains on these cars... I said you think so? He said "I know so". I don't have any evidence to back this up or to debunk it, so I just thought I would ask what others here thought. The only thing I could think of is that if the air has to be pushed through another pipe, then yeah maybe... then again... does it free up more air and produce more power because there are 2 ways out for the gasses?

 

ETS has a quad tipped dual exit exhaust on their 806whp X, I seriously doubt they would sacrifice hp when they also make a single exit.

All that matters is back pressure on a turbo exhaust. If you have a single 3" all the way back vs a 3" into 2x2.5", you actually decreased your pressure at a sooner stage. It's all about volume, and a single to dual can increase volume at a sooner point.

IMO, the only argument the single has is it's lighter. I do like the single more than the dual for that very reason, but not with our diffuser.

 

I honestly think the difference is most likely negligable and it just comes down to a matter of preference.

 

A well designed single exit exhaust, like the EVO8 exhaust will flow better than just about anything else. I realize this is an EVOX question.

There are poorly designed exhausts for the EVOs on the market. Our True Dual system for the X will flow as good as any single exit but still look correct in the back of the car and is lighter than most single exit systems out there.

Our cross flow is quiet and has two outlets too, I'd have guessed on our X that it would have lost power with our 35r kit on the car but it did not. I dyno'd back to back at 525 whp on pump gas and there was no difference, just a he'll of a lot quieter.

There is no straight answer to your question, it will depend on how each system is designed.

 

My answer will be much the same as above but let me add my $0.02

Fluid Mechanics theory for INCOMPRESSIBLE fluid flow states that head loss (back pressure) increases with every little geometer (bends, splits, fittings, baffles, etc.). Therefore an ideal system would be a smooth straight pipe out of you turbo. That is theory...

In practice, flow out of your exhaust is:
1. Compressible
2. Varying since our engines are revved through different ranges
3. Different densities due to humidity and ambient temperature changes
4. I'm sure there's more but can't remember them all

If you ask any PhD professor this same question he/she will say a single, smooth, straight pipe is best...and they'd be right. If you ask them if a dual exhaust could be as good in a practical application...they'd tell you that it would have to be tested (as any good tuner, product developer, engineer, mechanic would).

As above, I would have to agree that cold, hard data will beat theory every time. Get an exhaust from a reputable shop and don't worry if it's single or dual since power differences between the two would likely be difficult or impossible to detect (especially with a butt dyno). If you are going to race, go single since it's lighter. I'm still looking for an exhaust myself and cannot imagine a better one than the Buscher or ETS set ups since I need noise reduction where I live. If you can live with noise, go with their single exhausts..but Greddy or Tomei singles are probably good too.

 

I'm not looking for an exhaust, I have a TurboXS dual pipe set-up. I'm not going to change because it might net me 5 or 8 lbs less and maybe that much HP or less... I was just curious.

 

i think aesthetically the single exit designs look better. hp wise, i think they'd be around the same. you probably wouldn't feel a difference either way.

 

Wow, a little over my head but nice response for those who understand. I've always heard that going with the straightest single pipe would be the best bet. Lucky for me, I prefer the the look of the single as well.

 

Thanks for everyone's posts, very helpful. You seem very educated related to the different exhaust options available, I'm curious as to why you did not list AMS as an option?

 

I did not intentionally leave off AMS or any other make. Any reputable exhaust should be fine. My long winded point to make is that a single exhaust has the potential to have better flow (hence better performance) with the additional advantage of being lighter. However dual exhausts could easily flow just as well as singles. It's all about the dyno data.

 

... prove it. Seriously, there hasn't been any dyno proof yet.

In fact, CP-E went as far as to say they saw no difference between their dual and single. Which are more or less exactly the same exhaust.

 

This thread here is very interesting. I believe the only way to put any thoughts, doubts, or opinions to rest is by testing a single and dual exhaust from the same brand. Get them on a dyno and then post up the results. It is the only way this can be placed to rest.

 

We have ran both the single 3.5" exhaust and the Dual Exhaust, I would say under the 800whp mark.. your not going to see a difference in performance between the two.

Most dual exhaust systems start out with a 3.0" single mid pipe and transition into dual 3.0" pipes, if you do the math, it's over 3.5" in flow area. It's say your going to have a restriction with a 3.0" mid pipe and 3.5" rear section

You will most likely save on weight using the single version over the dual outlet mufflers.

Thanks!

Michael