A.Wayne

Yes

Jeremy Himsel

No really that big of a difference other then the potential (and likelyhood) of poping a headgasket, burning a valve, or cracking a cylinder every time you're under load.

It's two full points over where I'd run a turbo car and 1.5 over where I'd run a supercharged car under load and still higher then where I set up my NA's.

porschesam

Just to clarify. AFR readings were taken at the tailpipe. Car also has a 3 bar fuel pressure regulator. Turbo is a stock K28/8. Wastgate is stock. No shims or mods.

porschesam

I meant a K26/8

Ski

You should really get a proper WBO2, so that you can protect your investment; available from $300 to $600.

With the cat in place, whether it restricts flow - which can be attributed to another 1/2 to 1 psi if you upgrade, the car will run a bit rich compared to other applications with a full 3" exhaust. Case in Point: SFR full 3" exhaust with my car tuned from 11.7 - 12.3 ( onset of boost to redline). When I put my wifes "date" muffler on it ( factory exhaust with a pc made to fit over SFR pipe), my car returns to almost stock sound. But when you hit the boost with this combo, the AFR goes down to 11.2 to 11.7 across the board everytime I do it.

toddk911

Why is that??

Ski

It has to be for less flow/restriction. It does it everytime. But if increasing an exhaust size can add 1/2 to 1 psi of boost, then restricting it can cause it to decrease. Not going to ask NASA to investigate but we all know how a car spools better with a better exhaust. There is restriction in the factory muffler compared the bullett and 4" tip. I'm not moving the air as fast but the same amount of fuel is still going in. You can feel in the car a bit on the butt dyno, on spoolup.