I hope the 1000amp model is well sealed for when "Danger" does the testing! I guess water cooling would be relatively easy though
. On that subject, what about using a common clamp for the mosfets that was made out of square aluminum tubing that you could run cooling water through? That might be a little easier than making a manifold out of the heat spreader since it already has mounting holes running through it. Can heat be drawn out of either side of the mosfets effectively? Actually a finned aluminum clamp might work well for air-cooling...
Luke