Why would one buy catted down tubes? I would assume you would get a little louder. The web site you bought from has the answers you're looking for. It also says that it WILL NOT pass smog in most states with card standards. Better off going catless.
2012 Grabber blue, Auto, Eibach pro street S coilovers, MM caster/camber plates, Borla ATAK cat back, off road X pipe, A.E.M CAI, SCT-x4 Mike Roush tune,SR LCA's, BMR Relocation brackets, J&M Pan hard bar, UPR Catch can, SVE 15x10's, Mickey T's 275-60-15.