smi2ml

Hi I'm after a 3" turbo back exhaust (decated) but I don't want the usual loud noise that come with most after market exhaust systems, i don't mind it being slightly louder than stock but was wondering if anyone could suggest a quietish 3" inch exhaust system please? Thanks in advanced!

Trinity

iTrader: (28)

Revolution is the quietest i've found, was practically silent on my Type R, Cobra and Hyward also do track friendly systems

scooby kid

iTrader: (6)

just fitted a revo one, deffo exactly what your after

matt-c

iTrader: (5)

Milltek usually the quietest.

smi2ml

Ok thanks, an I wrong in thinking that if it's quiet like the standard exhaust then it doesn't give more performance? And is the revo one a "free flow" exhaust ? Or are all after market systems free flowing?

Trinity

iTrader: (28)

Thats wrong. Where as they are quiet than many Impreza system, they are DEFINITELY not the quietest by far.

I think you need to do a little more research and understand exhaust systems A larger exhaust reduces back pressure, which on a UK Impreza improves performance later on the rev range (but will hinder performance early on when the turbo needs the gasses to spool). When going for over 450bhp you will need a 3" as there is a lot to 'get out'

On a JDM Impreza and in fact many generally standard Imprezas a 2.5" is best and is by far enough to take you into 400bhp. I prefer early spool because we have a 70mph speed limit, why would you want more top end and therefore more lag? Common misconception that 3" exhausts are best. Always have a look at the rolling road graphs to compare the two - youll see the differences

the noise does not indicate performance - otherwise the council estate WRX chavs would be running ten second quarter miles with their drainpipes.

Revolution is a cat free exhaust, so yes 'free flow' as you say. You will need to choose a Sports Cat downpipe or decat downpipe (MOT Failure) to gain power, the exhaust on its own with Cats in place wont give too much.

Also gong to a 3" requires a remap.

smi2ml

Thanks for the info, I already have a decat pipe and then the standard sti 2.5inch exhaust, I am hoping to achieve 380bhp in the summer, so do you think my existing exhaust set up is ok for 380bhp? My car is a impeza 2.5 STI 2007, I was always thinking that I had to "upgrade" my standard exhaust. ?

Trinity

iTrader: (28)

So you are changing turbos and probably forging the bottom end?

a true 2.5" system will perform fine for 380 in my opinion.

I'd get a sports cat, sounds like you still have the original cat in the downpipe which wont do you any favours.

If you want more top end, but more lag early on, change to a 3".

Tidgy

Scoobyclinic do a full 3 inch system thats designed for keeping within noise limits on track, had one on my hawk and having one on my R, had a nice bark when you hit the loud pedal but not mega loud or droney at motorway speeds

smi2ml

Hi it's the standard turbo, but many people have said that it will produce 380bhp. I have had forged pistons, and the exhaust it completely decated, I'm wondering if a after market 2.5 inch exhaust system is actually needed if I have had the original cat removed ?

smi2ml

Ok thanks, if I have had the cat removed then do you think I will need to change the rest of the standard sti exhaust if I'm aiming for 380 bhp?

matt-c

iTrader: (5)

Perhaps i should have said "in my experience" thought that was a given though.

However, in my experience revolution was the loudest exhaust i have personally had.

Of course there are many other factors such as cat's, resonated sections etc.

frayz

iTrader: (7)

Simpson Race Exhausts built mine, it's quieter than stock and flows plenty still at 570bhp

Tidgy

yep, cats are very restrictive

RAVENLEON

iTrader: (4)

The Jetex system from Evolution gets my vote!

brendy76

iTrader: (6)

3" + freeflowing should never = quiet

smi2ml

I have already had the cat removed but was wondering if i needed to also change the rest of of the standard 2.5 inch standard sti exhaust?

joe v3sti

iTrader: (8)

Really impressed with quality of my jetex system, fitted really well! Haven't heard it running yet but they are supposed to be very quite

Trinity

iTrader: (28)

Revolution are made by Jetex

you have two cats smi2ml, you need them both removed which you dont currently have, therefore you need a sports cat downpipe.

and the 2.5" will be FINE for your purpose, spend your money more wisely on the sports cat.

Trinity

iTrader: (28)

Ive yet to see one make 380 on the standard turbo, but I could be wrong.

What downpipe are you using then if you are completely decatted?

smi2ml

Hi there are no cats on the vehicle, the decat pipe is quite a long pipe that goes from the turbo right down to underneath the car , it looks like the one below: API engines fitted this pipe when they done the forged pistons

Tidgy

linky no worky

smi2ml

Hi it was fitted by API engines , i think its an unbranded one but seems to be working fine, the turbo cuts in almost strait away. So am i right in thinking that if i attatch an aftermarket 2.5 inch (decat pipe back) exhaust then it will be add no extra performance as the one thats on there is already the standard 2.5 inch STI exhaust..

smi2ml

Hi, quite a few people have advised that they have had 380bhp on their standard Hawkeye STi turbo with porter headers, uprated fuel pump, and 3" decat exhaust...

jaygsi

iTrader: (46)

I have a cat back system brand new 3" bore quiet forsale

Trinity

iTrader: (28)

Advised or have rolling road print outs from a reputable rolling road, not a crappy chav one that ups the duty to show a bigger figure

smi2ml

No i havnt seen the dyno printouts but they all said that thy got 380bhp, with ported headers, decat 3" exhaust, Walbro fuel pump and remapped by Bob Rawle..

smi2ml

I always thought that i would need a bigger turbo to get over 330 bhp on a hawkeye, Maybe it depends on the mapper on what power you get..

smi2ml

Please can you advise the make and price? do you have a photo?

jaygsi

iTrader: (46)

https://www.scoobynet.com/subaru-par...e-milltek.html