i searched no luck, are the intake ports any bigger compaired to ls1 intake ports. im going to port a buddys heads and he was going to get a ls6 intake but i couldnt find if theres any differnce in the size of them. thanks. i mean the opening not the runners if that makes sence. im wanting to gasket match;.

 

the sizes are the same, its a direct bolt on. The LS6 will add about 5-8 RWHP to a car with the old LS1 manifold. It'll combine to add alot more if you have a cam, and up to about 18rwhp when you're running an aggressive cam with high flowing heads.