The letters are moulded on top of the fibreglass, thus having a flat surface underneath. So if you sanded them flat id say it would leave a smooth finish but reckon you have to get it paited after as the sanded part would look completly different to the rest of the heatsheild.

personally i prefer it with the turbo lettering.

Most carbon fibre turbo covers come with a flat surface (no lettering, or lines).