Will I notice a difference with 2.75" exhaust

[DarrenM]

depends how well its made as some have been that restrictive that it causes more harm than good (darrenm's exhaust springs to mind)

This is very true, when i bought my S2 it had a Longlife 2.5 cat back system on it but it was well restictive and gave a nasty boom at a certain revs (not a deep drone from having a bigger system but a NASTY restrictive noise that could be causing more harm than good).

I took it to the nearest Longlife to me (although the system was fitted at a Longlife up north) and we discovered it was 2.5" and brought down to 2" over the rear axle. A really bad result anyway!!

Ended up scrapping the whole system and got 3" turbo back, single backbox/race cat from Corey (thats another story all together but we wont go there!)

LOUD as fooook for everyday use but no restriction and ideal for what I wanted.

[20Vcqdriver]

shall we have a show of hands then??...

No prob, I'll go for a 3B 3" downpipe. Can ask Ian Birch at Pipewerx regards prices and how it drops with numbers made when I see him in a couple of weeks time (Only fitting the system for now until I know what I am doing with the engine spec next year). Isn't the ABY downpipe different, i.e goes to a Y section for the cats?!

[Jamo]

All 3" downpipes should be single output the Y-Pipe is a restriction that should be removed

That way it's generic to 3B and ABY

[europeanme]

All 3" downpipes should be single output the Y-Pipe is a restriction that should be removed

That way it's generic to 3B and ABY

good thinking!!...

[Jamo]

Prospeed can make the 3" downpipe they made one for Rusty, be worth approaching them for a group buy if Rusty can confirm the downpipe is good.

I did request pics from him but think he's afraid of getting dirt in his finger nails since his appearance in the national press

[Ross]

My 3" downpipe was made by my local longlife, just a few miles out of gloucester. Their downpipe is pretty good - proved it to 430hp - cost £300 but could be worth asking them what they could do, say, a batch of 5 for.

Shame mine is now back on the car as it would have been ideal as a template. Only issue is it's designed for the Garrett hotside which is a few mm longer. Fits OK on my K24 now though...

Agree 100% on the crappy systems comments, the london Longlife had fitted a nasty backbox on my Avant's 3" system that sounded like a jet at full boost and started to melt the rear bumper! Replaced with a magnaflow backbox, quite alot louder but sounds damn good on full chat.

[MGaz]

No prob, I'll go for a 3B 3" downpipe. Can ask Ian Birch at Pipewerx regards prices and how it drops with numbers made when I see him in a couple of weeks time (Only fitting the system for now until I know what I am doing with the engine spec next year). Isn't the ABY downpipe different, i.e goes to a Y section for the cats?!

sorry for reviving an old thread, but just wondering did you get your 2.75" exhaust in the end?

I know Custom auto craft do a 2.75" system. with mandrel bends, & if its anything like my CAC 2.5" system they sold me, its very lightweight compared to standard, so i at least know i saved some weight when it was fitted..

[20Vcqdriver]

Had a long chat with Ian Birch and the result was that if I am definately not aiming to exceed 360-380bhp, then the 2.5" freeflow system with a properly matched 3" downpipe would surfice and keep booming down to a minimum too. Once past this though and go straight to 3" throughout...
Made a massive difference to mine. Attached is the latest vid with car estimated to be around 290-300bhp.. Private road of course..
http://s718.photobucket.com/albums/w...Apr2010045.flv

[MGaz]

Had a long chat with Ian Birch and the result was that if I am definately not aiming to exceed 360-380bhp, then the 2.5" freeflow system with a properly matched 3" downpipe would surfice and keep booming down to a minimum too. Once past this though and go straight to 3" throughout...
Made a massive difference to mine. Attached is the latest vid with car estimated to be around 290-300bhp.. Private road of course..
http://s718.photobucket.com/albums/w...Apr2010045.flv

so you're now running a 2.5"inch exhaust then.

good to know i wont need to replace my CAC 2.5 incher then! it cost me enough.

[S2central.net]

Here's a funny thing - I know of several S2/S4 machines happily blowing circa 420bhp on stock exhausts with just a bigger EM and 3" downpipe (bigger turbos too of course). I thought it was generally accepted that a 3" exhaust was only required for power levels significantly higher than that. My memory could be a bit fuzzy though.

We all get towards ~300bhp with factory 2.5" downpipe, CATs and system with a good ECU.

A chipped RS2 running 2.75" downpipe and better EM, still with CATs and otherwise same exhaust as S2 Avant blows towards ~400bhp so I think the exhaust builders will tend to lowball their estimates for obvious reasons.