you need a powerpipe or something to get that boost higher. I know your sig says homemade power pipe, what is homemade about it, are you losing pressure before the Maf? are there any leaks etc. I would buy a premanumfactured(reputable) pipe to hold the boost. And just my opinion but i think that Holley intake is a bit much on those heads, and can't that cause pressure drop across the board.
jason
jason