Fran, Freez was going to try a Raptor ignition module on the XT with that we be able to move the RPM. Steve_athens has a racing ECU on his bike with the standard ECU removed & his rev limiter is at 8500RPM.
I have not pushed for this mod as we have not built a XT motor that I know of that will make it's peak HP after 7200rpm. You also create a whole lot of other problems when you get the XT motor to produce it's peak HP beyond 7200 rpm with a high lift camshaft, I think I experienced it with my stage 1 Hot Cam on the dyno. The valves may start to float at those high RPM's with the standard springs with a high lift cam, you will need to remove the cylinder head & fit up rated valve springs & retainers to prevent this.
Freez is the best person to ask about this mod, as he has done it many times.
http://www.atomicmall.com/view.php?id=253509