Another thing Rodimus, whilst the inlet manifold is being worked on...
You will likely find the inlet and exhaust manifold are two different thicknesses, and most people have a cock-eyed thick exhaust washer or welded cut halves of washers on the fixing stud/nut trying to make up the difference in height when fitting both to the engine. Not a good seal and a bodge. I had my inlet manifold fly cut/milled where the correct Nissan thick exhaust washers would go on the inlet so it was the same thickness as the exhaust (I have a picture but can't find [did post it on here years ago]), this way you get proper clamping force onto the engine head ports.