so from what Ive gathered is the exhaust diameter helped the popping. im running 3" straight now instead of 2.5" diameter. currently I have the stock downpipe to 3" aluminized single exit. straight pipe only. I went with 3" over 2.5" because im installing my new efr turbo & manifold soon. 2.5" is plenty for stock turbo and mild power levels. I prefer 3" dia for anything track raced and putting down 300+ but that's just my opinion. I currently backfire and produce 1-2ft flames a majority of the time between 2k rpm and up shifts. I am currently running a pro tune (freektune), 2j cowl intake, and the exhaust setup. with a catless dp, you will probably see more popping and etc. I think it sounds great the way it is now with the stock down pipe. but like I said, its going big turbo this week if I get my car into my shop at some point.