floridamale

The pre cats on my 87 came loose inside the pipe and the noise dose sound like a knocking from the crankcase until I listen to it with a 2 ft long 1/4 drive extension resting on the pipe just before the pre cat. Had then cut out and new pipe welded in there place. If your going to remove the Y pipe make sure you soak down the manifold bolts for a day or two with a penetrating liquid before you try loosing them. Run the car a few times in between spraying them heat helps it soak in.