My old Mustang had the non-Mach system and sounded like crap. As soon as I replaced the head unit with an aftermarket I noticed HUGE differences. I thought it sounded really good. That's just my opinion though, I'm not a subs kind of guy. Just the right amount of bass is perfect. Not too much, not too little.
2000 Mustang GT!!!
FRPP Intake manifold, Flowmaster 40's with larger pipes and tips (Nice deep tone).
"I want to own a shop where people can come and not get completely ripped off" - Ludacris (Fast Five)