There are several people on this board and others experimenting with the Yamaha RX1 and Apex snowmobile engines. Steve Henry (of dead stick takeoff fame) has an Apex engine on his current Highlander and the performance is breathtaking. These engines are capable of near 300 hp in a snowmobile and in aircraft tune are making 140+ reliable hp (without a turbo or nitrous) at slightly more weight than a Rotax 912 100 hp.