ORIGINAL: arobatx
I know the power from the G62 can get pretty insane when on a cannister or tuned pipe, with some minor mods to adjust squish and porting. I've seen exhaust changes do more than other mods thus far, but I am curious about your project.
My G-62's power went insane just on a good exhaust, no porting. If you let the engine breath it can make some real power. Yes my Yak is not a warbird but at 7800 rpm on a Vess 23A it can still make some good speed. Acceleration on mine of course is better since the aerobat only weighs 17 lbs full of fuel.
The point is to try to find an exhaust that will allow the 62cc's to giddyup and then a prop that can move air. My choice would be the Vess 22B on a G-62 on a good stock exhaust.
Edit Here is what a G-62 can do when breathing good air, no porting changes just a pipe.
http://www.youtube.com/watch?v=jbQcD9cYRDQ
http://www.youtube.com/watch?v=jps3cDMJnm4