I have a catback, from Thermal R&D. Everyone really likes the way it sounds, cause it produces a deep steady tone and doesn't sound like a weedeater. Prices range from $400-600 for a complete cat-back, but if you just want a good looking exhuast with a deep sound, you can opt for the axleback system. I have also heard Greddy Evo, and it produces reasonable gains, and sounds fine. Tanabe, sounds too much like a stereotypical import, it's loud and annoying. Apexi's dunk system sounds alright, but can be pretty costly.