I have done alot of ignition work on race two stroke engines
Jetskis as my name would suggest

At the top end of the curve about 6000 rpm on wards you need to turn your timing back
this will heat up your tuned chamber (assuming you are using a tuned pipe) and increase the speed of the sonic wave
which returns a pulse back to your exhaust port sooner and allows the pipe to keep reving on
this is worth a lot in overrev for your engine
try it you will be suprised
Here is the curve i use on my 800cc two stroke