I'm looking for a set of heads for my 502. Which brand is the best for a boat and wich gives the most HP.

Bang and Quality for the Buck! Go with a set of the Dart Pro1 Marine aluminum heads with a 325cc intake port, should be about the best choice for your needs, unless you are going with some huge cubic inches or large compression or bigger than useful camshaft. My 2 Cents.

Best Regards,
Ray @ Raylar

The new AFR 295 oval are due out soon! Call Bob at Marine Kinetics and talk to him on this, he's an AFR dealer now.

The AFR 315 CNC is a fantastic head for that size engine. It's good supercharged too. One member here has done 1100 hp with a pair on a 540.

All my friends have made great power with AFR.