Pipe Myth Or Pipe Fact
#31
#34
Be wary of the freezing trick, if you have a big dent and you freeze a few cycles to get it out, it's possible the the divergent cone (the one inside) to become disconnected from the wall of the pipe. If that moves around in the pipe while you're running the effect can range from bad tuning problems to engine damage if you attempt to "tune the problem away" for too long.