A 415 ci marine engine with VVT from Mast Motorsports. I don't know whether they are partnering with Raylar on this one. 536 HP @ 5800 RPM; 523 TQ @ 4800 RPM.

What does the low end torque curve look like. Say at around 3000-4000 rpm? Cost? Time to rebuild?

Looks like the Raylar motor. Cool stuff.

From the website...

Our LSM550 engine is now 430cubic inch and it was dyno tested with all marine equipment including raw water pumps, closed cooling, marine headers in place versus an automotive engine configuration on the dyno. I know that if this 415 cu. inch engine here is fully marine configured its horsepower and torque values will be more like 500HP and 490ft/lbs of torque. Not bad, but its still not ready in this state to drop in a boat so don't think you are going to see a completely equipped 500HP marine LS engine in the $15-18K range. This engine is also equipped with our forged crankshafts, special forged pistons and other special components to produce this kind of durability. If it could be done with stock GM components , ours would already be priced in that range. Mast is working with us to expand our marine LS offerings and were hard at work building LSM550's as we speak and some lesser powered versions soon to be released.
Boat speed costs money! How fast do you want to Go!

Best Regards,
Ray @ Raylar