Bringing this in from the Engineering forum. http://www.pit-lane.biz/t117-gp125-caracteristiques-aprilia-rsa Might want to throw it in Google Translator. Starts off in French and some Dutch, page 17 it goes to English and gets good, Frits Overmars jumps in on that page and starts giving some spectatular info. He worked many years with legendary tuner Jan Thiel. How cool is this stuff? How about 54 hp 125's. The powerband isn't nearly as horrifically narrow as often mentioned, the best one is making more hp than 125 dirt bikes make at peak for over 4000 rpm. How about some 3D porting Dual exhaust ports (there are even some with 4 ports). Gives more even heat distribution in the cylinder, better scavanging, etc. Plus, you get dual pipes, which is just cool/weird/different, although no way god for dirt.