I've never seen an Acme prop on a Moomba, at least not from the factory. It's possible the dealers may have changed them. OJ has had the contract for quite awhile now.

I have the OJ wakeboard prop and have the growl as well, doesn't bother me enough to re-prop and works just fine.

Altitude does play a great difference in performance, enough to to drop top end. I boat at no greater than 1,000' so i see no diff at all but many at higher altitudes re-prop to compensate.