So which one? I am tired of the straight pipe noise. I find myself lugging the truck with trailer way to much in small towns trying like hell not to let the local cops hear me. Now its time for a FlowMaster, I have been reading Flowmasters website a little bit. But I do recall some heated discussions a while back about which muffler to use. Dual, Single chambers who gets the nod here? The 40 series says its good up to 1000 hp Oo.