Know Marty well. He does an awesome job on 2.5L.
FYI he will not touch a 3L. Been there done that. Call Eric Simon at Simon Motorsports. Had a 31' Fountain with 225hp 3L and ended up with close to 300hp. Motors ran great never had a problem with the powerhead. Just keep in mind the motor mounts and mid section/lower units were not built for 300hp.
You can also a Brucato intake system that gave my boat another 30hp.
In the end we had Boysen Reeds, Heads, 300x PCU/ECU's Brucato Intake System/ Coils and wires.