on the "rossi-tuned" version i mean the only difference in that and the standard motor is port-timing exhaust-timing and crank size .....also that the tuned version has the nice coating and treatment on the internals ...its not like he laid hands on them and did anything to them ....inmho .....mark at powerhouse rc performance ...has spec'd out each motor and found this to be true ....check his thread out here and search through the last coup,e of pages ......
http://www.rctech.net/forum/nitro-of...ngines-46.html

i few pages back he goes into more detail about it