I don't have a full cat-back exhaust, but I have an APEX'i N1 Muffler and NO resonator, I just had the guy weld a straight pipe in it's place...removing the resonator doesn't neccessarily make it sound fuzzy or rattle. It depends on the car....but my '00 'Teg doesn't fuzz or rattle. Yes, removing it will make it loud, but you don't lose anything from removing it.