Manny knows what hes doin there. he wouldnt steer ya wronge. the Trick Flow heads imo are better designed to with stand huge power demands than the MMR heads. MMR doesnt have the best of rep. with the oil pumps eather.
Trick Flow have better flow ported intake chambers than the MMR MMR have more left over tool marks and not to mention the gaskets seat better with the Trick Flow heads.