Gains can be made with anything. As a bolt on HP swap, no. The rect's move everything up in the powerband. Ovals bring them back down to a more managable rpm band. You might feel a performance advantage, but it's not an increase in HP, just putting things back to a reasonable, workable area of the engine's capability to work this engine where you have control of how you work it. I say this because you just told me it is in your boat. Depending on prop pitch and varieties of props you might change over to etc, the 049's will give you versatility in performance on the water with what ever plane system you're running and the amount of skiers you run (gotta get them out of the water smooth and quick). What out-drive do you have? You have to consider that. It really blows when you're out on the water and the darn thing breaks or gives you fits because of an engine that was too tempermental at the wrong time. Do a bit of research on these heads and mull it over. I think you'll be happier with the 049's.