I would definitily touch base with Eddie Young. He's not that far from you. If its reliability you seek, he will make them reliable. No guess work.

http://www.youngperformancemarine.com/

Wow, you got 500 hours out of them? I have a pair of '05's with 140 hours & wondered what I could expect. Any major repair during the 500 hour stretch?

I've heard great things about HTG Racing rebuilding 575's.

I bought the boat a year ago but knew the shop that did all the work. The engines did have some blower issues, and one did blow a head gasket. Other than that, nothing major on the engines. From all the drive problems he had it wasn't ran easy. I ran them this year and other than two sets of plugs, didn't put a wrench on them. Ran out great with no oil consumption. These engines are mild and the blowers only push about 4 psi. I'm just wanting to freshen before a major failure.

Brad Smith Racing, located in Joplin Missouri is among the best builders of Supercat motors. He builds the vast majority of MTI engines that actually last. He took my SC 600s and upgraded them to 750s. The motors are much more efficient now. They actually make more power now with less boost and heat.