Im not sure if my car is back firing, or there's just a lot of built up back pressure in the exhaust. But when my car is completely warmed up and the exhaust is hot, sometimes when down shifting, it will pop really loud like gun fire and occasionally throw flames. I think thats normal for a full 3in turbo back exhaust, because I've seen it on many other cars i know were running fine. What i am a little concerned for, is when im slowing down to a light/stop sign ect when in gear (usually 2nd), my car will make a really loud "pop" like a gun shot at exactly 1500 RPM's almost every time. Im not sure if that's built up back pressure exiting the exhaust, or a back fire. My tune is a tad bit rich but it runs fine. Is it an issue or is it normal like i think?