Rodney,

The most cost effective method, for getting 400-1,000 extra RPM (depending on the prop), is by exchanging the muffler to a Tower/Hobbico .46 unit.

This addition will appear over the 'baffle removed' numbers and will be larger if the baffle is still in the original 783 muffler.

Other changes will be much more expensive and you would probably better off just buying an MVVS .49, an Irvine .53, a Rossi .45 and for High $ mods, a Jett.