I noticed that my tpi gasket kti came with two different intake manifold gaskets. One set had the rear most port blocked off and one didn't. I don't know what this is called but I assume it is a coolent passage. The ports look like and are just smaller than the actual intake ports in the gasket and are the first and last major hole on the gasket.

Why are there two differnt versions and which one should I use for my application (see sig)?

If I should use the one that has it blocked off, do I block off the front or the back passage??

:hail: Help me

 

Coolant only goes through the front of the manifold. This means don't block off the front passage.