just my opinion but i love my setup if you can find my soundclip i posted awhile back.i did p/s x pipe then dual dynomax mufflers.i used the straight through 1s ,they have 2 that are in identical boxes 1 is a s chamber the other is straight through that i used make sure you open the box and look u could easily get mixed up .look for the sound clip i love my system.hope it helps,good luck.
mods:2004 sierra ext sb,20s ,big brake kit w,hawk pads,air bagged,2006 6.0 lq4 swap,vortec supercharged10psi, air to water intercooled w/ dual electric fans on it ,snow meth injection kit,60lbers, e-fans ,big radiator swap ,cam 218 /222 548/550 comp .hardened prs .1.85 comp roller rockers ,guideplates ,crane double springs,trans 4l65e built .pacesetter l/ts true duals w/x pipe and magnaflows,14 bolt rearend swap ,3.73s,aroemotive fuel pump system w/elec.fuel controller and bypass regulator a/n fittings, taylor 10.5s interceptor gauge,aem w/b a/f ,autometer boost/vac NELSON 93 OCTANE TUNED .