i just got my head back from my local machine shop, and it was cleaned and melted. And the guy who did this for me said that i can use a stock 2j hg. i already got one but freinds of mine advised me to get a metal hg.so my question is would the 2j stock hg work just fine or should i buy a aftermarket metal hg,and also my goal is to break into the 400-450 whp range.