I think they're all pretty good these days, if dealer support is better go with the Merc.
IMO always power to the max hp
Pretty hard to hurt a engine by feeding it more air. It's just a washer with holes in it that restrict the air running into the motor. Engines like air!
Actually the fasted way to melt a piston is to lean an engine out...........unfortunately this is something I have much experience in LOL
If your simply making more power by leaning out the engine its very short lived gains..............
My money says the ecms will have different part #s (the lower hp one may be able to be flashed but?) because more HP will require more fuel curve for long term survival.