my buddy has a 96 gt running 350 rwhp n/a with the 4.6 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif anyways we put a simple 10 in. sealed in his car wit one seat down and like 250rms.. bumped like Id expect it to.. As for as big systems go the only problem I can see with a mustang is that its a small car, crack the windows n see if it gets louder...