i just made this pipe from a polini expansion chamber treats has athttp://www.treatland.tv/rizzato-polini-fifty-pipe-p/rizzato-polini-pipe-200.0040.htm
just welded my own header to it . and did a little bending.this pipe rips pretty good and its fairly quiet.i know there has been talk lately about people wanting pipes that arent as loud as the mamba etc i have a cimatti city bike and it was basicly a bolt on. i have a polini 75cc kit minarelli hi comp head from 1977peds,modifed intake and spacer (20mm),21mm phbg carb red foam filter and 10x42 gearing and im hitting about 50 on the gps