The BEST exhaust system for your car would be a 2.5" Milltek catback. Available from Courtenay Sport. Before I had the SC, fitting the Milltek gained me 12lbs torque and 5bhp. The torque was the noticeable difference because you can actually feel the torque.
The sound is awesome too! Not too noisey. Just a nice deep conservative sound.
Milltek.............For the more Decerning Enthusiast!!
;-)