K03s exhaust dimension indecision

[A3 Oly]

hi all,

I am about to have my exhaust upgraded to a 3"dp to sports cat to cat back stainless.

I've decided that I don't want a full 3" system so will be stepping down from the 3"dp to 2.5/2.25.

Is there any major gain in going for a 2.5 over a 2.25 cat back?

Many thanks in advance

 

[<tuffty/>]

Most after market and custom systems are 2.5".. std S3 system is 2.5" and thats 210/225ps out the factory

<tuffty/>

 

[VAG-Slag]

Cue Bill @badger5 - "It's all about the flow"

Seriously though, every little helps... And when tuning a turbo car I would expect 2.5" to be an absolute minimum, even on a tiny k03 turbo

 

[A3 Oly]

Thanks chaps, I thought that would be the consensus.

I'm gonna go for the 2.5!

I just have the reasonably priced dp off turbo revs but having the rest of the system custom made. The turbo revs pipe drops to 2.25 after the drop to 2.5 so will get the garage to cut the pipe and flange at the 2.5 part.

Then a tasty remap!!

 

[A3 Oly]

So just to update,
Fitted my 3" downpipe fairly painlessly and with a good amount of wd40 and a hot engine (and some blisters lol) ready for the system install on Friday.

Had a 2.5 sports cat and full system fitted..... Wonderful feel to the car in the low end. However really needs a map now. Looking at now more than 230-240 bhp. I'm not after s huge powered car just something that brings a smile to my face.

Not sure people's opinions on this but I had it done at powerflow in Mansfield. I have seen mixed internet reviews on powerflow but my friend with a Evo 10 had his system done there and its spot on. The work they did to mine is also spot on can't fault it and did exactly as I asked.

So big thumbs up to Mr tyre in Mansfield for a powerflow install.

This is on my aum golf gti, my a3 agu was part chopped many years back now in favour of a stupid idea of getting a sensible car, needless to say that didn't last long.