Yo! I just installed a 3" single cat back exhaust with magnaflow muffler (2.5" inlet to 4" out). It sounds great, I couldn't be happier! My car is a S5 N/A. She used to purrrr at idle, now, im getting poping noises. There are no exhaust leaks so I'm curious as to what causes this? Is this normal for us N/A guys? I want to make sure no damage is occuring. Should I be messing with the air/fuel mixture? Thanks for any help!!

 

It's backfiring, this is normal and happens a lot. You probably just couldn't hear it because of your stock exhaust.