It's not validation, it's correlation. I said i don't know what the impact would be. OK, just checked my mustang. No plastic push pins. 10/32 screws and rivits from the aluminum skirt to the plastic rocker, and then to the steel jacking rail welded to the pinch/rocker. Most definitely. When i was an MX-5 cup engineer, we raced with IMSA as a support series. I chatted with the head Porsche GTLM engineer for awhile and he told me that they wax their cars before qualifying for this very reason. As you know, drag increases with the square of speed, so the average speed around the track isn't the important bit for factoring skin friction drag.