Need help. I'm trying to figure out what exhaust system or what particular part of the exhaust system is responsible for giving that popping/crackling sound on deceleration. I've changed my exhaust system up a couple times trying to find it but so far...no dice. Right now I have Bassanni headers with a Bassanni X-pipe through 2.5" inlet/outlet Borla S Type mufflers w/ no cats. This current set up sounds good but it doesn't quite produce that sound I'm talking about. I'm starting to think it's catalytic converters in conjunction with the rest of the exhaust that gives the exhaust sound I'm talking about. Can someone clear this up for me? What should I be looking for or doing different to get this sound that is so popular on our cars and Mustangs in general really, especially late model stuff.