Well I just got back from spring break in London and after seeing all of those mopeds and scooters and whatnot, i just HAD to go and mess with mine as soon as i got home. i just started welding last week, so i figured i'd try and do something that'd give me a bit of practice. i used the javapipe tuned pipe designer (http://beadec1.ea.bs.dlr.de/Airfoils/tpipedes.htm) to figure out the dimensions. went to menards and spent 20 bucks on metal and spent two days in the garage. the result? MUCH nicer than the leo vinci exhaust i had before (i think the exhaust i bought was meant for a peugeot scooter and not moped). increased performance all around, and higher top speed (maybe 3-5mph?(i dont have a speedometer..)). the only problem, WAY too loud..sounded like a weed wacker. so i went back into the garage and improvised a silencer out of what i remembered from other exhaust pipes. I put it on and now it runs great ANd is almost as quiet as before. I recommend to anyone who has any welding skill at all to try building one of these..doesnt take too much effort, just a bit of time.