Exhaust - 2.5" Vs 3.0"

[diogocartier]

Guys,

During the next month I´ll assembly my car.

RS2 turbo + Fuel Injector + remap + intake hoses & exhaust.

What should I go, 2.5 or 3?
why?

Best regards,

Diogo.

[rynaqui]

I think 2.5" is enough but larger downpipe than stock will help. RS2 (2.75") or custom made. I don't think a 3" system would hurt though

[20Vcqdriver]

What power you aiming to end up with? 2.5" is good to about 350bhp if free flowing silencers and no cat. Add a 3" downpipe to same system and you should be good to about 420bhp, after this I think you'll need to go 3" all the way... Just going on my own experience....

[diogocartier]

My goal is to hit 380~400bhp...
it will be full system on 2.5" with just one muffler...

i think that 3" will be too louder...

The down pipe on 3" is a good choice?

I´m afraid that 2.5" can be to small..

rgds!

[filip.krticka]

Do not forget, that RS2 has 2,75"

exhaust system loudness is not question od 2" or 3" diameter, but silencer, which have to be installed

3" will be a bit boomy, but power needs larger diameter.

My vote is 3" togeter with metallic cat and two silencers.

[caterpillar]

att least 3"... or bigger... ive tryed both... no cat.. only on big box in the rear... dual tailpipes.. jepp in 3"... leave about 25-40mm clearance to the chassi...

[Rusty]

You'll need a bigger turbo for that power bracket... Either an RS2 hybrid or a K26/7.

Go 3" for the exhaust. If you want it to resonate less then drop the diameter towards the rear box, it seems to quieten them down a bit by interrupting the standing waves and thus changing the tuning frequency of the exhaust. I'd go 3" to the rear seats and then 2.75" to the rear box. I run 3" and 2.5" with a single box and it's not much louder than stock in the car.

[John B]

You'll need a bigger turbo for that power bracket... Either an RS2 hybrid or a K26/7.

Go 3" for the exhaust. If you want it to resonate less then drop the diameter towards the rear box, it seems to quieten them down a bit by interrupting the standing waves and thus changing the tuning frequency of the exhaust. I'd go 3" to the rear seats and then 2.75" to the rear box. I run 3" and 2.5" with a single box and it's not much louder than stock in the car.

I used to have a 2.5" Milltek which was subtle even without cats. I now have a 3" custom, which does resonate more but is quietened a little by a sports cat and the 2 boxes.

K24 hybrid or K26/7 is the way to go if you want plug and play.

JB

[caterpillar]

ive even tryed 4" on a old mercedes, from 3"... and the turbo come over 600rpm earlier... 2600rpm with 3" and with 4" from 2000rpm...i was shocked...

[diogocartier]

I'm convinced...
I'm going with 3"

Thank you all!