At the beginning i thought that this project would be fine with a catted downpipe and OEM cat back.
Then i got that central resonator is very restrictive. It retains heat, that is not good for turbo, and apart from this it causes high backpressure. So the way to go would be a resonator delete, but you probably already know that for me it's no go.
So the aftermarket resonator i found (a muffler to be precise) is bigger than stock resonator, like someone already found out, and at this point the only way to go would be create a complete custom cat back to fit in everything in the right place. So I did.
In this configuration now I have 3'' Milltek catted downpipe, 5x9x15'' vibrant performance muffler used as resonator (with 3'' straight through pipe) and 2,5'' pipes to OEM back mufflers.
Now backpressure and heat problems are solved, and I feel the car maybe something faster. But maybe it's only my impression, so I will dyno the car again and see.
As for the sound and noise I am not disappointed at all: the sound is slightly better than before, and it’s definitely not noisy.
Inside it sounds the same as with OEM resonator, cruising at low revs you can barely hear the engine. Outside I can hear the difference. Not big difference, but you can clearly hear there's something different under the hood.
I have to thank Aaron from Vibrant Performance who has had the patience to explain and show me the best product for my needs. Just to know, the muffler I installed is part #1127 “Streetpower Oval Muffler”.
This was the stock catback:
This is the custom catback installed:
Here is the Vibrant Performance #1127 that barely fitted in
Complete exhaust