Mercury Marine has now created it's own V8 - 4 cams, 4 valves per cylinder and 552 cid. It's rated at up to 1650hp, all for only $65,000.00!
http://www.mercuryracing.com/sterndrives/hp1350/features.php
http://www.mercuryracing.com/sterndrives/hp1350/features.php