When my 66 289 is sitting at idle or excelerating while driving I hear what sounds like an exhaust leak from the passengers side. When at a steady speed it seems to go away. The best I can tell is that is seems to be comming from the where the exhaust and manifold meet. The drivers side seems fine. I have loosened and retightend the connection between the two and it still seems to do it. Could it be the donut gaskets, are there better ones than what came with the FelPro kit. When in neutral and increasing the RPMs it seems to disappear once I get to a certain RPM, or I just can't hear it anymore. Any help would be appreciated.