+1 for the APS being hard to find, took me forever to find mine. I had no clearance issues with mine and the exhaust came with EVERYTHING I needed to bolt it up. I've been running it for over 50,000 miles now and am well pleased.

I never had a 3" exhaust on the car so I can't really compare. I do know one thing though, my exhaust sounds really really good and I'm happy with it. Is there a big enough advantage to justify it's extra cost though?? If I were doing it all over again knowing what I know now, I would have probably just went with a 3" TBE and used the money I saved for other mods, but hey I'm happy with it. It still is holding up like the day I bought it and looks great..

 

in turbo cars, bigger is better. wether you'd make more power, probrably not without more boost and a larger turbo. in turbo cars, boost produces torque, not backpressure. the turbine gives all the backpressure you need.

 

i built 2 exhausts for my car, one a 3" and one a 4"...i'll do a back to back next week when i dyno hopefully. Its not an Evo but a 2.0L honda. We have done a few 3.5" and 4" aluminum exhausts on Evo's but no comparisons yet...

 

Uhh shepard's car is 1100 HP+, you can hardly consider anyone in this forum anywhere close to that.

 

Actually, your wrong. If you look at any dyno sheet, a higher flowing manifold, exhaust cam, head, exhaust piping, always results in lower end torque/power and a larger top end. Yes the bigger piping will net more power but it won't yield much since the car we are talking about isn't powerful enough to BENEFIT from such a large exhaust. For there to be a substantial increase in power, the current exhaust has to be acting as a bottle neck. A 3 INCH EXHAUST IS NOT A BOTTLE NECK for A 300-400 HP CAR. Going to 3 4 5 6 7 8 inch exhaust will not yield any power. Think of it this way. Lets say you live in in the middle of no where. On your daily commute to work you typically see 2 other cars on the road. If they decided to build a free way in your area, do you think it would allow you to get work work faster? NO. Thats because there wasn't that much traffic to begin with. If your car isn't flowing that much exhaust gases, why the hell do you need more volume to flow it through?

 

3.5" exhaust is overkill on a stock turbo, period. If you can run 3.5" off the hot side of the turbo then do it but I know the stock turbo is much smaller than that already.

Stay with a 3" and dont waste your money. When you upgrade your turbo to something huge sell your 3" in the classifieds and go with something better. Until then, put your mod money toward something else.

 

Whats the point of bolting a 3.5" downpipe to a 2.25" turbo elbow??

 

but can a 3.5" o2 housing be made? or will there be any issues?

 

GUYS, this has all been tested before.

David Bushur gained a whopping 1HP when he took his 3'' exhaust completely off. This was on a car that had 300+WHP

 

Thank you.

 

I've heard nothing but good things about the HPF 3.5" exhaust and its proven power gains. I'd traded my set up for it in a second.

 

did he lose any torque? i'm doubting it even though sonicfadz thinks you would.

 

Uhhh, I didn't say you would lose torque. I said you lose bottom end torque, and gain on the top end.

 

sorry, didn't see the bottom end part. but i still believe that under full boost you won't lose torque anywhere from 3500+. you might lose some off boost torque, but i hardly think it would be noticeable.

 

Actually, I think you're wrong. On any turbo car, you'd ideally run no exhuast for maximum power, spool up, etc. Anything that restricts the exhaust flow through and out of the turbine will slow down spool. Granted, on a stock turbo car, you won't see much difference, but there will be a difference.

All the stuff you listed is BEFORE the turbo. Higher flowing manifold = high volume = lower exhaust velocity for a given mass flow rate = slower spool. Basically the same as using a bigger A/R turbine housing. Longer duration cams hurt lowend, head work generally increase the flow area which inturn reduces flow velocity through the ports which hurts lowend.

Even on NA, you don't want backpressure. It just happens that you need to keep exhaust velocites high for scavaging effects.... and to keep it high at low engine speeds means smaller diameter tubes which means higher backpressure. It's not the backpressure 'creating' torque, its the exhaust scavaging from the higher exhaust velocities.