Was changing the oil on my bike last night and noticed I had an exhaust leak (due to the fact that the exhaist really dies not fit properly but I digress) When I pulled the Head pipe I noticed that where it joined the muffler pipe there was a poorly fitting ring welded insode there that did not look good for flow at all. A bit of time griding and whacking it with a hammer and chisel got it out of there, and the result seems to be a tad more mid range punch but this may be due the exhaust sealing properly now.