I have spintechs in a Roush Side Exhaust configuration, using the 333SCS mufflers.
i ****ing love them. there is no mustang ive heard in my life that sounds as good, and im still on the stock Hpipe. my only gripe is its not as loud, i go to the track, and while my exhaust tone is 100x better than any other car, the loudness factor just isnt there. then i got to my cobra and its ****ing loud(bassani x-pipe and catback), but the tone sucks.