There is no frame grinding required on a 300 kit...I have ran both the 250 and now currently the 300 kit. With a 240-250 kit you will have to grind the inside of the chain side of the frame to clear the chain, not a good think in my mind. But, the 300 kits are desinged to eliminate that. More than likely you will not be able to run an unmodified exhaust that has a muffler on it, this is why most run the Brock's or Boz systems, as a standard exhaust won't clear the swingarm. You could retain your exhaust system, but you would have to have a custom bent pipe made to clear the swingarm and a spacer to push the muffler away from the swingarm.