ive taken the smog pump off every mustang ive had, and for some reason never had a problem....the guy putting my motor in said there are 2 threaded holes, one on the back side of each head....he said that if they arent plugged then there will be a serious exhaust leak....and sure enough i saw the holes my self....so i went out in the garage where my buddies stock heads were, and his do not have anything like that...What gives? he thought it was where the smog pump may have conected..... ....anyone have to do this before and know what size fits it?
btw the motor is a 93' and my buddies is a 91'
btw the motor is a 93' and my buddies is a 91'