Get some buffing compound that is safe for what ever coating or plating that is on your pipe and then apply some elbow-grease or rent/buy a buffer and go nuts. Also the price of a new pipe varies on whether you buy a full system or slip on or if its fitted or a universal and whether it is a brand name or a knock off. If your not looking at getting more power out of your bike just buff the stock pipe but remember that if you do get a new pipe that you should get your bike properly tuned to get the power gains that you pay for in a aftermarket pipe.