New heads

Losing power going Aluminum was a Big worry that you'd lose power when aluminum heads started becoming popular, I wouldn't say the evidence against is conclusive but there been a few test when companies offered a cast and aluminum version no one found any loss, and like worrying if a stoker gonna wear your engine out, it seem to be an old concern most don't care about anymore, aluminum heads seems to work for 90+% of the aftermarket and the car industry as a whole.