That's A hot rod WEBRA .55 and A tuned muffler the owner supplyed. I don't know the make of the muffler but when I was the pit man for him and he had the engine in another plane it brought the RPM way up on it. I can't remember how much but it was A lot. My problem with it is the weight of the muffler, I think he could get A lighter one and still get the RPMs he likes. As I recall the rules forbid tuned pipes and that was the reason for this type of muffler. He plans on comming out at the end of the month and giving it the maiden so I have to get in gear and finish it up for him. This one I'm not going to maiden for him, I suspect A rocket with A wing from this little guy.