I think John_Z has dyno's before and after he's now running OEM with better results than the single he had before. I think it was the 70mm.

 

John ran both a 70 and 80 mm single, but is back to stock now.

 

This would now be the case with turbo though...

 

Yeah, hopefully switching to the 2.5" at the split didn't hurt too much. It's definitely a lot quieter (which was my goal). Bisi said that it's almost like my previous "true" 3" exhaust but with longer piping. Which may lead to running a little richer. I'd still be happy at 490ish rwhp if I should lose some. At least for now. After switching out the HG, I'm going in for the speed/psi tune.

 

damn...
i just bought the t1r 70mm ...
should i change to a smaller one, since i am super charged too?

 

I'm in the same position, well not yet but when I install my supercharger. I don't know, i'll probably just run the 70mm because I like how it sounds better and give up the whp lol. I don't really wanna go back to stock exhaust.

 

honestly i hate stock exhaust.
heavy and don't look good, especially i have full j's racing cf body kit, so the rear bumper it's kinda high, and u can see the whole muffler , so ewwwww..

but i just gave my tuner a PM about this, i hope he PM me back of what he knows..
my Tuner : www.Evanstuning.com
Great Tuner....

 

what i dont understand is the 3in>70mm but 60>3in

 

3inch>70mm>63mm was my initial theory !
But nope its more like 60mm>3inch>70mm .

 

Interesting!
I am running a supercharger
I recently switched from asm 70mm single to amuse 70mm->50mm split dual

I noticed a midrange gain with my butt dyno... I thought it was just my imagination till I saw this thread!