Dar,

Comparing the Hatori line of reflector disc pipes (generally considered the standard by which others are judged and manufacturers choose as OEM) we notice that the diameters are the same (40mm) from the 10cc 'short stroke' model 601 to the 10cc 'long stroke' model 650 and even on to the 'super long' model 700 and the even longer (9500 RPM) Hanno pipe. The only major difference is the location of the first reflector disc after the diverging cone inside the hollow pipe. There is also a silencing/muffler section after the disc to help reduce the noise.

Terry in LP