[COP TZER]

So i just had my exhaust put on yesterday afternoon, and of course i needed to go for a rip. My friend was driving just to the back right of me and said that when i was shifting between low gears at high rpm at WOT that i was popping out a small flame every once in a while...WTF[:I]. I know some people pay money for this, but i'm just wondering WTF is going on?? Any ideas??