Really, how much of a bottle neck is a dual 2.5 inch exhaust compared to a dual 3 inch exhaust? I read on alot of sales pitches on companies that make 2.5's and 3's and claim the 2.5's are good for around 500hp. If thats true why are there alot of 600hp 4 bangers out there with single 3 inch exhausts. The reason i'm asking is I may be going to a 2.5 dual exhaust for a quieter and cleaner look. Thanks

 

Whats the point of twins and 2.5 " piping. If it was me, i woulda went 3.5 inch piping. let the car breathe.

 

3.5" lol i got 4" lol

 

I know that "bigger is better" in the turbo world but, i drive on the street and want a quieter better fitting exhaust. This is my 3rd aftermarket exhaust-borla, sfr with hks mufflers, and svr-tech. I like the way the borla fit and sounded compared to the other two but want better flow. So if there is anyone out there who went from a 3 inch dual to a 2.5 inch dual i would like their opinion. Will there be a significant difference in HP with the 2.5?

 

only 2.5" I would consider is the aps 2.5". You might also want to consider the greddy evoTT

I fully understand your intentions. dual 3" is much too loud.

I made decent power with the aps.

 

There is nothing wrong with a decent 2.5" exhaust 3" is just to loud for a daily driver. As zivman said go with aps 2.5, greddy evo TT wich is louder than aps. I have a stillen with the X pipe removed and it flows fine. It all depends on what you want. You really can't compare a 4 banger to a V6.

 

Thanks for the advice. The APS dual is the one i am considering. The 3inch exhausts are loud and have clearance issues.

 

Not all 3" have clearance issues. My APS fits good. OP-if your not looking for crazy power (don't lnow what you make now) then just switch back to the Borla. 20 or even 30whp at the 500 plus level isn't huge.

 

3" and wear ear plugs? jk

 

I'll chime in on this one. I have run an HKS Dual Ti and swapped to a custom 3" straight pipe exhaust and while the butt dyno doesn't say much the shrink of exhaust hiccups is evident. I would get the exhaust pop with 2.5" exhaust and now it just gurgles (TT 500RWHP)

 

2.5 is plenty for high hp

 

The bottleneck IMO is the Intake (plenum side), Heads, Cams, and Headers... HP tends to drop off @ 6200, but can be made beyond 6200 if these are addressed. Or... You could always just throw more boost at it to overcome the flow restrictions.

 

I switched out my APS 2.5 test pipes/Injen 2.5 exhaust FOR the 3.5 APS test pipes and Greddy EvoTT exhaust and went from 390whp to 425whp(on my stock motor at the time) on the same dyno. Just a side not: I did stretch open the bottle neck in the EvoTT exhaust also

 

I LOVE the gurgle

 

did you just use a tail pipe expander to do that??

 

well damn, maybe if it was a turbo deisel.

 

When you swapped out for the greddy, how much boost increase did you see? I doubt you made 35 hp at the same boost levels?

 

so do i. when i pull up to people (vettes) they just look like WTF? combine that with open dumps and it's insane noise **** for the ears. doesn't touch the Ferrari note but it's sexy

 

well my car sounds like a Ferrari on crack.... I hope it only gets better

 

What about dual 3" with a pair of huge resonators or even four resonators?
Will it still be that loud?