I had this exact same thing happen to my Muzzys... Do this:While the pipe is still hot (like after a ride) take some "0000" super fine steel wool to it, just rub back and fourth and it will come right off and more importantly it will not scratch your pipe. I was totally scared to do it myself from fear of scratching the pipe but trust me it worked great and did not leave any scratches.
Might see how well oven cleaner works.
How do you get it into an oven?