I'd say the Pro .46 is a great choice for anything like the OMP.

I've got one in my Sledge and have more than enough power for everything. Pull out from a hover is good. Your OMP will be lighter... I am a BIG fan of the Thunder Tiger engines. This is probably number 13...All have been perfect, all have ran great, and ALL have taken my abuse! Oddly, they have all been used engines too!

If you're going to be buying another engine though, and want the BEST, I don't think too many can argue against the YS .63...

It's weighs 2 ounces more than the Pro .46 and I'll guess it can produce twice as much thrust. At least, it seems like it!!

Depending on how important 2 ounces is to you, the Saito .72 might be the best choice.

I really don't think you can go wrong with any decent .40-.50 2 stroke or .70 4 stroke...