Take a look here:

http://forums.nasioc.com/forums/

exhaust.

turboxs makes a classic turbo-back system.  the turbo back consists of
downpipe, midpipe, resonator pipe, and muffler.  the muffler is aka an
"axle back."  a "cat back" system goes up to the midpipe, where the
last of the factory cats is.  depending on your viewpoints of keeping
cats on your car, you can free up a moderate (20) to a large amount
(30+) of horsepower.

hth
ken

My first upgrade is going to be a Cobb Tuning Accessport
(www.cobbtuning.com). It's a ECU reflash that allows you to reflash your
chip once and then change maps on the fly. The recommended base map (if you
don't have a catless downpipe) is either their 91 octane or 93 octane stage
1 map, which, according to Cobb's numbers, adds 25 hp to your car off the
bat. The great part of the AccessPort is it's built to allow safe tuning
based on your upgrades, so if down the road I get a catless downpipe, I can
change to the Stage 2 map and gain a lot more power. If you don't want to
tune the car yourself or get it tuned on a dyno by a pro, the AccessPort is
the way to go. It's around $600 right now and very backordered because they
can't keep up with the demand. I ordered mine 2 months ago and I'm still
waiting, but most people agree that it's one of the best first mods you can
get for your car because Cobb is a trusted tuner (they only work with
Subarus) and you can download new maps based on your car set up once you
start adding mods.

Jen :: The Vodkinator