Has anyone used or heard any good coments on thease new hy-flow heads that are floating around everyware for sale. they are 64cc 200 intake runner-2.02-1.60 bare for around 500.00 a set. I'm looking for a new set of heads for a small chevy buildup and need to get 500+hp. I'm thinking of going with pro topline iron or maybe thease new so called hy-flow heads-need some feed back fast before i buy!!!!!