With clear 8-mil? No, no loss whatsoever. With the lights on and looking at the headlight covers, the slight Lamin-X orange peel is apparent, but it does not cause any loss of output. You noticed output loss? Were you using 26 mil yellow or dark smoke?
If you can, get 8-mil VentureShield or something other than Lamin-X. Lamin-X films have more orange-peel than others. VentureShield is the smoothest of them all. Try
http://www.stickercity.com/ It is easy to cut it to size if you get a bulk sheet.