I have a Borla Turbo Muffler
where its 2.5" SI/SO straight through design. Now at about 3 grand it gets fairly loud in cab, but it sounds mean the whole RPM band it never gets raspy or cheap sounding. I also have JBA headers so that might affect it some how but I never ran the borla without the headers.
I also have all my Pipe upgraded to 2.5" instead of the stock 2 1/4 and 2"...
Anyway, Mines loud, and sort of annoying at 3 grand, but I dont really worry bout it.