Exhaust advice


Registered User
Hi lads

I have a 3” downpipe and sports cat that tapers down to 2.5” and sleeves into a 2.75” Milltek with a reducer.

So the whole exhaust system goes from 3” to 2.5” to 2.75” which is a bit of a bottleneck.

Is this okay or should I consider changing the set up?
Depends what your cars running dude and what car it is.

If it’s a standard S3 then yeah it’s fine. If it’s remapped, ideally do away with the bottle neck. If your running over 350bhp you want 3” from start to finish really.

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Registered User
Thanks man, appreciate it

Its an S3 BAM and the guy I bought it off said it was mapped, at that point it just had the milltek.

It’s now got a Ramair cone filter, B5 TIP, downpipe and sports cat

I’m planning on getting it mapped again once I get an Airtec FMIC. That’s as far as I’ll go in terms of mods tbh

I couldn’t seem to find any that taper down to 2.75, is my best bet getting a shop to remove the 2.5 taper and weld on a 2.75 ?


Registered User
That’s it thank you mate, doubt it’ll be much for a shop to chop the 2.5” sleeve off and weld that on to the sports cat I have already

I couldn’t find any sports cats online that taper into 2.75, Only option I could find was a milltek decat twin pipe that fits the OEM downpipe and comes down into the milltek cat back. Unless you know any?