other than the 4 exhaust ports, what's the function of this hole that is situated behind the breather pipe.
looks to have EGR functionality but here in australia the C22SEL motor in the vectras never came with the EGR valve, so is that hole useless??
i'm making up an exhaust manifold and i was wondering if i need to grind a bit out so exhaust gas can be sucked from the adjacent port?
i have a pic, but i cannot host it