I put the Green Air filter like they showed in the video in my C7 and MPG decreased 10%. I put the OEM one back in and started getting the same gas mileage as before. Not sure if I just got a bad product or what, but as of now I'm running the stock filter in mine. But thanks for the video, that would have been helpful when I did mine.
Keep in mind that the C7 engine uses a dynamic ECU so the ECU is constantly making adjustments to the fuel flow and other parameters as time goes on. It may take as long as 500 miles before a real difference is noted. I installed the Airaid synthamax green air filter and also noticed a drop in fuel mileage for about 250 miles after which my fuel mileage increased to above what it was with the stock air filter. I use a Top Tier fuel I my car. Premium with no ethanol added.