I've had this gauge installed for about a month now to complement my SC install and hopefully keep my engine safe. When I was dyno tuned my AF was 11.5-11.1 (low to high rpm) across the range. This was using shop's WB and it is many times more expensive and undergoes frequent calibration. The WB bung was installed after the cat, so it should be reading leaner than normal if anything. The sensor for my cobalt gauge was installed in the same bung after the dyno time was finished. So while at the track this past Saturday, I had my eyes glued to my WB to detect potential problems because I know my injectors are at 100% DC at 6000+ rpm. The readings didn't seem to make any sense. The gauge was reading 10.0-10.5 at WOT, anywhere from 0.5-1.0 point richer than the dyno data. Since I know my injectors were maxed during tuning, how could the mixture be richer than during the dyno tuning? It can't. The air was more dense during the track day compared to the dyno day to boot, which should have resulted in a leaner mixture because the fueling is fixed. For $369.99 I think I have a glorified idiot light with +/- one full point accuracy.