I have heard you need an oem downpipe with this catback?

First of all, what is oem, just the type of gasket? second, which downpipe would fit with this catback; helix, turboXS?

 

stock uses a doughnut

 

I had a friend who had that catback. It matted to a perrin downpipe nicely, but had fitment problems with the helix downpipe.
TurboXS dp tend to only mate up with turboXS catbacks.
You could also use the oem (stock) downpipe as well. Just don't forget to get yourself a 3'in, 2 bolt gasket.

 

alright what about perrin downpipe with borla hush catback? just trying to get an idea of fitments here

 

They both mate up without any problems.

I know one guy who rocks that setup and he loves it.

 

i like the subtle sound the hush makes, somewhat throaty and deep at idle, and a nice smooth sound when it's opened up. your friend who "rocks" the perrin downpipe, does it sound a little louder/meaner with the downpipe installed? given how quiet the hush is, i suppose there's always a little more room for some more growl :-)

 

It sounds nice no doubt. If you don't mind the dual tips then the hush it right for you. Quit at idle, except when WOT. He said it's just about the same. Maybe a tad louder.