I use 3M paint film under the down tube, 2 small pieces on either side of the headtube, and one one the DS chainstay. Works very well and is almost invisible. I say almost because you can see the edges of the film if the light hits it just right, but usually not the film itself. I kept the leftovers from when I had paint film applied to my Corvette, and have plenty left for several bikes. It doesn't take much.