There is a metal gasket between the manifold and the Pre-cat, and it has 2 sides to it. One side is smooth, and the other side has a crease to it. Does anybody know which side goes against the manifold, or does it matter?

 

Do you mean between the motor and the manifold ? The crease goes to the manifold . The ones I have seen between the center casting and the precat are not folded and only go one way because of the the bolt pattern .

 

Ya thats what I meant, and thanks

 

Crimped side goes toward the manifold. The reason being that there are holes cut out for the egr port.