UNLESS you were planning on running a bigger turbo or a lot of boost later in the future.

You probably wont notice the power difference from a 2.5-3in. Especially if you run an extra (particularly chambered muffler) on it. I would say running a cat all the time, a straight through resonator/muffler such as a magnaflow (eliminates the high tones), and a chambered muffler, such as a turbo muffler.. Or for looks the chambered muffler then a fart can round straight through..

either way you will get plenty of back pressure from a cat and 2 mufflers..

Good luck
Andrew

 

Since your question is answered, its got me thinking now about my setup/future setup. My milltek system is 2.75" from the down pipe back. So I retain my stock DP and cat. When I put on my 3" test pipe, its going to be 3" TP - 2" (stock) DP - 2.75" Milltek resonated. I wonder what thats going to do for my performance....? hopefuly not bad things..

 

Would this be loud though, I'm going for barely noticable under normal driving conditions and on the freeway. Under full throttle I could care less about sound, I just want it quiet inside the car.

 

well i think he dp stock is 2.25 but its not gunna really hurt anything, thats how I ran my set up and no probs

 

Your performance will increase one8, Miltek did testing showing the 2.5 inch downpipe was best for the 2.75 exhaust for maximum power from the quttro system, so I would imagine the 2inch will be fine or you could get a $30 downpipe made in a 2.5 inch. They told me notto go any larger than a 2.5inch downpipe with the stock turbo but if I ran a large turbo to switch to a 3 inch downpipe with the 3 inch testpipe and a 2.75 exhaust.

 

Thanks good to know.

 

I would probably go with a 3"dp, 2.75 tp, and 2.75 piping through the back.

 

on my car i had 2.5dp and a 3" after that.