Nice question,
Difficult answer, but I am afraid you left it open. First, I think all the OS guys might be a bit dissapointed but the Rossi 46 will easily out pull the OS engines size for size anytime. But even better why worry about those little ole 46's, now there is a 52-53 (8.5cc) in many lines. Same case, same mounting dimensions. And for reference the Rossi factory spec says 2.1HP at that same 16,000 (which it easily turns on a 10x6 prop) and 2.3 hp for the 53.

So if you really want the HP open up your scope of engines, those Italians are not left behind very often!

oh, by the way, the Rossi spec sheet also lists the .40 at 2.3/21,000 which I have seen on a 9x6 rev up prop and 15% nitro.

So if you want the grunt, look for more displacement, if you want the speed, then check out the 6.5cc

Jimnie