I'm getting the Drag Gen3 kit soon and I'm still debating whether to go with a 3" exhaust setup including a 3" downpipe, 3" carsound cat and 3" TR&D catback. Or, should I go with a 2.5"?
How much performance gain will I be seeing with 3" vs. 2.5"? How much louder is the 3" setup?

Thanks!

 

Backpressure is your biggest enemy when it comes to Turbo'd engines.
3" is far better, and would net some good power gains.

 

Exactly, 2.5" is too restrictive though it would work.........but you may have minor problems from it. 3" is much better for providing max power/psi on a turbo system.

 

OK. But how much louder is a 3" setup?

 

It is a bit louder, in a deep tone, but most people can stand it. Especially if you compare it to a big exhaust on a V8, it is quieter than that.

 

keep in mind with the drag manifold the way it is, you wont be able to regulate
boost and your minimum boost level will most likely go up, probably change
your base boost to almost a bar

 

How exactly does that work Steve? With a *bad* manifold and the 3" exhaust. Thanks!

 

Are you talking about boost creep?

Hmm, I don't have first hand experience, but I've been running with a STOCK exhaust with my turbo for a while now with no real problems. I have heard that 3" is very much louder than a 2.5" I think I might go with the Apexi WS...that's a 2.5", right? I heard it's quiet.

 

the drag manifold vents from the #1 runner only pretty much, which is more
or less fine for low boost apps.
However with a real free flowing exh(such as 2.5-3") the exhaust will have
a much greater tendency to go into the collector and through the turbo
rather than go UP the #1 runner to the wastegate.

 

Apexi WS is 60mm which is about 2.3XX inches......

 

apex ws is ~2.36" and it is quiet, but not a straight-thru design. with the 3" setup you might boost creep a bit. even with my tial wg my boost level crept ~.5 psi and i only have a 2.75" dp w/ 3" all the way back. 0.5 creeping is ok w/ me tho.

 

I see, so if you had a 3" setup with a manifold that had the wastegate set up differently spiking would not be a problem?

 

right

 

i have a Blitz cat back with 2.75'' piping...that wont make any considerable difference under a 3'' would it ?

 

so what would you say a good solution is to correct this in reguards to the manifold?

 

What a lot of people have been doing is sealing the wastegate port and moving the
wastegate to the collector.

 

Okay....dumb question. Where/what is the collector? The only other opening is for the actual turbo, right?

 

i've heard of boost spiking when upgrading to a 3"exhaust w/3"dp....otherwise changing the manifold will get rid of it...typical of the drag 3?

 

there are a few reasons why i went with a 2.5 exhaust. (1)not as loud as a 3in exhaust. (2)to prevent unnecessary boost creep (3)price!

however, a 3in exhaust system gives you a little bit more power... better performance...

 

Is there a way to make the 3" more quiet like by welding on a longer resonater? How big is the Thermal Research 3" turbo exhaust tip? I might have them or a local shop weld on a 3" tip instead.

 

Actually I think it is more than a "little bit" more HP. Someone has to have a dyno chart showing this. Anyhow, I think even for a Honda 3" is the right size when using a turbo.