i'm wanting a new cat back exhaust for my 05 wrx. i've got a magnex back box now, but want something a bit louder. i've got 2 young kids, so it can't be too loud.

how loud would it be with a 3'' pipe?

i don't want it to resonate around the cabin

would the 2.5'' pipe be adequate?

i think i need to have a listen to a few

 

Its not about the internal diameter. The cats and the construction of the back box (silencer - big clue here) play the biggest part on the sound front.

As long as your not planning on 400bhp + then a 2.5 system should be fine.

Ge to a local subaru meet, find one that you like the sound/look of and ask when system they are running.

I have a full hayward and scott system (no cats) with a resonated center section. Its pleasent on m/way cruise, and around town it keeps the sound levels under control until you put your foot down.

 

i'm not planning big power. i've seen one at exhaustsuk £180 cat back, and i can have 2.5 or 3 pipe.