I have been thinking of doing the same since I almost never use the sunroof. There is a CF sunroof delete panel on ebay for 260.00. It basically gets glued in from the inside with some RTV silicone type glue and you can remove the roof mechanism to save 40lbs. Obviously if this isn't done properly it will leak.
http://www.ebay.com/itm/Carbon-fiber...b0fe2d&vxp=mtr