if youre staying with stock manifolds and cats, id go with the loudmouth, simply for the good gains you will get from the straight-thru resonator design. if youre going to headers and/or u plan on ditching your cats, definitely not the loudmouth. and its not even the noise level, its the annoying rasp u will get.

go to ls1sounds.com and check out some loudmouth clips on there. stock manifold/catted cars sound amazing with the loudmouth, but header/ory pipe cars have a lotta rasp. if you plan on doing headers/ory, id go with either hooker or magnaflow, two of the best flowing and sounding catbacks on the market. hope this helps out a little.