stealth heads vs edelbrock heads

my dad has the cnc'd stealth heads on his belvedere, and my brother has the regular ones on his challenger. my brother did a little work on them his own by hand and his car dyno'd at 550hp with well over 600lbs of tq. pump gas runs great. he has a street strip cam 500+ ci stroker kit also from 440 source. my dads car was not dyno'd. they have had zero problems with the heads