Possible yes, practical no. Would entail boring/pistons/carb./manifold/prop. changes(at least).<br />Would 10HP be worth the expense? Prob. not...<br />Suggest you trade-in your 40 towards a new(used) 50 if you really desire this additional HP.<br />My $.02 worth...run what ya brung, still haven't caught any fish at 40MPH!