you wont loose any power mate as I think a single 2.5 would be better suited to your car twin 2.25 equals to aprox a 3.18 inch single system which is a hell of alot of flow for a na 6 you need some back pressure, I have fitted a redback 2.5 inch with 2 hi flow mufflers to a ed it sounded nice not loud just deep, I have hurd a n/a ba xr6 on youtube with a xr6t exhaust I quit liked the sound but everyone is differant, my mate has pacey headers-hiflow cat-2.5 with 1 muffler and a hot dog on his ba fairmont it sounds tuff but its pritty loud I recon you would be best off with a twin muffler 2.5 inch like this http://www.bestmufflers.com/bshop/product_...c7c44cfc1eb7298