ProMaxx and IMM aluminum small block LA heads

They sell a lot of Promaxx heads at the local machine shop…. Never heard of any big issues with them… lots street sbm builds pass through the place….the as cast heads seem to dyno in the 400-475hp range and the CNC shockers 500-580hp depending on the build…saying that if I lived in the USA I would buy the heads IMM sells just for the fact I always support small business when I can…