3" or 2 3/4" Exhaust for St-R, what is best and why?

[kiwited]

Hello

I am currently making up my mind which exhaust to chuck on my 2.5 ST-R, I was advised that the 3" is too big, causes the turbo to over spool - whatever that is -that 2 & 3/4" is perfect for 2.5 four cylinder.

Can anyone shed light on this? I am keen to get several second opinions!

Regards

Ted

 

[bods]

Can't overboost unless the wastegate gets stuck open, which can happen but doesn't very often. The just is still out in which size is "the best" but apparently some models of yd25 can't fit any bigger than a 2-3/4" dump pipe anyway

 

[Farmer Joe]

I have been told that 3" is too big for my 3ltr also. They recon you still need a bit of back pressure, so I am in two frames of mind also of what size to go for. For the records I have been advised to use a cast dump pipe because the steel ones don't last very long before they crack!!

 

[Gonzo]

I have the 2,3/4 . No probs ! I have had people say that your front shaft will foul with the 3 inch . When 4 wheeling .

 

[BIG GUS]

What Farmer Joe said,you still need a bit of back pressure,so 2 1/2 to 2 3/4 is perfect.

 

[Dion]

back pressure

When will this crap die off? It's got to be the deepest rooted myth going around.

 

[75 GRC]

I've got a 2 1/2 inch sports system on mine. Sounds sweet, still have backpressure. And it's got a nice note. And 2 3/4 would be the biggest I would go (personally) Unless you were chasing A more beefier sound. G

 

[TigerST]

Turbos dont need back pressure because the turbo dosent need to spin backwards. The Bigger you go the lourder you go. Thats about it.

 

[gazza414]

When will this crap die off? It's got to be the deepest rooted myth going around.

couldn't agree more....same as religion...if enough people preach the BS its taken as truth

 

[gazza414]

original thread starter using the search function is your friend..otherwise this thread will be filled with nothing more than copied opinions once again

 

[JOE_D22]

On my 3.0L i have a 3" mandrel bent turbo back with a highflow muffler, awesome note, great response, if you want an expert opinion, talk to a 'few' exhaust shops and see what they think.

 

[ben85]

3" cos its bigger and better

 

[mike1303]

Why go 2.5? It has one on there...

Why pay the huge price of the brand name 2 3/4"

3" works just as well it sounds tough and more often then not allot cheaper!!!!

 

[rabbit-chop]

The right amount of back pressure on a turbo exhaust is none, so bigger is better, but 2.5" is as big as necessary on these low output engines. Most important thing is to have a nice dump pipe, high flow (or no) cat, and straight through (or no) muffler.

 

[rabbit-chop]

And mandrel bends, not pressed, with smooth radii

 

[TigerST]

A 3" straight pipe

 

[kiwited]

Great replies!

Thank you all

Ted

 

[xtturbo]

3" no mufflers. I'm currently running a "housing commission cat back", eg nothing at all after the dump/cat pipe, and my snorkel is louder!

 

[350zx]

I'm running a 3inch system, and a 3inch dump pipe. It was a pig of a thing to mark and install, its got a nice sound and better spool (seat of yours pants mind you). I went 3inch cos I could buy it thru work dirt cheap.

And I've been 4wd with in, and nothing hits it.

 

[bert546]

have a look at the exhausts on a top fuel dragster . i dont think there would much back pressure what ever that is there.