i am running a vortec compatible manifold that i bought off of Ebay. i was a bit leary when i bought it but it was a decent price so i went for it anyway. ive been running the setup for aout 1 year now and the only problem i have had was the gas was getting a little on the warm side and pre detonating. i put a spacer between the carb and the intake and it solved the problem. if you are going to use an aftermarket vortec specific intake, buy one with the "air gap" option. this will eliminate the need for the spacer.