I've placed a Saito 56 4 Stroke on my Nexstar. You have to use a 12in or less prop for ground clearance, but it works well. Takeoff run is a little longer, but she purrs along and sounds great. It has plenty of power and balances out very similar to the OS 46 engine even though the Saito 56 weighs more (?????). I even used the stock Nexstar engine mount, but you'll have to dremel out the mixture adjuster. Good luck.