Hey I was bored while I was driving today and was thinking. Why not machine off the reeds and intake area and add a gear driven supercharger. This would boost the pressure up and should be able to fit under the stock hoods.
Imaging a 6 psi boost on a 800 twin. Unlike nitros or the turbo you could use a regular clutching technique since the power is linear.
With this forced induction the pipes may be able to be changed too.