I have a GT-40 crate motor and typhoon upper and lower intake manifolds. What can I do so I dont have a vacuum leak, most likely from the lower intake or I may not be getting vac to the egr because of a bad valve in the back left corner. also, can I reuse a lower intake gasket if not ruined. if not, does anyone have suggestions or part #'s for the lower gaskets? By the way, I believe this vac problem is causing intake backfire.