Both look great, Bosal hangs a bit low without any mods to the hangers. Sound Quality, from what ive seen/heard the Bosal is Louder and the Borla is a nicer growl but both are top notch. Borla is gonna cost you about 200 bucks more tho. Personally im going with BOSAL because the Borla is way to much.
Edit: because there is such a sudden intrest in the Bosal system, maybe someone should look into getting a group buy together, i would soooo be down with that.
