No matter what you do, don't touch the exhaust port.
Here's a 3-page article all about engine porting & timing
http://www.rcnitro.com/rn/articles/engine_timing.asp


here's a link about porting & polishing
http://www.nitrorc.com/mods/engines/...ngine_mods.htm

Another with more/better pictures:
http://www.nitrorc.com/mods/engines/trx15mod.html


Don't touch the exhaust port! Modifying the exhaust port requires some very precise equipment to measure & change the various angles involved. The connecting rod / crankshaft mods also require a certain amount of equipment + knowledge to avoid screwing up. Best bet is to see if you can find someone local (through the forum) who's done this before. I've been reading up on this too & it doesn't seem very tough. Good Luck!