Thanks. Now do I bore it or leave it stock or can I get a muffler shop to make one? Does it make much difference? I tried searches and found a little but not much information. I like the D&D that's on it and would like to keep it. It currently has a holeshot advancer,unknown jets(the PO just stuck bigger ones in), and the airboxcover removed. It runs pretty well but seems to idle rough and bogs a little when I crack the throttle. I tried an X with duct tape on the airbox and it stalled at 5k RPMs. The advancer definitely added some power. It seems real close but I'm not sure where to start but for some reason I have to play with it. I'm more interested in low to mid torque\power than top end HP. Thanks for your help.