my buddy from work drives a 93 1500 4x4, and as far as i know his only mod was flowmaster duals. thing sounds real nice and he doesnt even have headers. the new mustangs, 99-04, i havent really heard any REALLY nice sounding ones other than the 03-04 cobras. havent heard the new ones with aftermarket exhaust but i think they sound pretty good stock. the 94-98 ones are all bark and no bite, **** those things are slow. the 87-93's sound MEANER THAN SHIT. love the way those cars sound with headers, h pipe and something like borla or bassani exhaust. super mean.