I think this will explain about the intake manifold problem I experienced. I was not there when the problem was corrected, but from what my dealer, James, explained to me, this seems the only place where the problem could have occurred. He reads here sometimes, so hopefully, he'll correct me if I am wrong. :) I think the important thing to do is ensure that the "pipe" is tightly snug to the carburetor in all places, as a defective clamp might lead you to believe it is fully tight, yet gaps could exist that would allow air to leak in..