I just put a new XR600R FMF power bomb header on my 650L and seem to have a leak. I know other guys are using this header so I know it will work. If anyone knows how to get a better seal, please do tell. I thought I was having a jetting problem, well, I still might have a little problem, but I'm going to put in a #55 slow jet . I thought I had a different problem with the mid-range power but I bet that is from the leak. If anyone has any input I sure could use it.