You don't need to setttle for the finish provided by the manufacturer. I should have mentioned that a better way to re-contour the covers is with an exhaust pipe expander. I didn't have one large enough but I may pick one up and redo it. Harbor Freight has an inexpensive one that should do fine:
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http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=37354[/FONT]