I tried to search but didint get my answer my gsr is built and after getting it tunned i changed my cat to get smoged and put my test pipe back in today and under full throtle it was back firing with a flame every time i got back on the throtle until i slowed down the guy i raced said there was a flame, i dont think it has to do with running rich cause its tuned but im not sure if its normal any help would be great.