You said you got your intake manifold from a newer Camaro SS right? I don't know much about LSX engines but one of my co-workers is building a twin turbo LSX motor to put in one of his older Camaros. He also had a intake manifold from a newer Camaro but ended up trading it for a older plastic intake (not sure what it was from). He said the newer ones are built with more pieces and one of the gaskets is known for failing under pressure. Have you looked into this? It might not be something to worry about at your boost level because his goal for the project was to be "substantially faster than his 1000cc road course bike".
Awesome build BTW! Love all the fab work.