I just recently got a driven innovations intake manifold and the flange is extremely thick. I also got a phenolic spacer gasket and was informed that I will need longer studs for the head than stock.

what size will I need or where can I get a longer stud/bolt kit for what I need?

 

The intake manifold uses 12mm bolts, except for 2 14mm studs. I'd take one of the 12mm bolts to a hardware store to find longer ones. As for the studs, you'll probably have to remove one, measure the thread pitch and order them.