I have 99 GT with a 2.5 pipe from the cat to the stock y and no mufflers and it sounds sweet once its warm and only rasps in first gear when you let off the gas to fast, so I dont. And I have the car gutted from the front seats back so the drone is crazy!!! LOL!!! I made an axle back with dual glass-packed mufflers to dual dual glass-packed tips that I can remove at the track and there is 0 rasp any time. The drone is still there a bit but not near as bad mostly cuz the car is gutted. And if I put another glass pack where the res was there would be no drone. I noticed that drone is also allot less the farther the tips are sticking out of the car but it looks like ass so I settled for 1 inch out.

I'm no expert, just curious and this is what I found while I was playing with the exaust.