I have an extremely difficult time believing that he was able to boost his fuel economy by 13.3mpg (a 37.4% increase) by ONLY flashing his tune on his car, driving in exactly the same way, with exactly the same route in exactly the same conditions, making full round trips.
There isn't enough information in that first post to determine whether or not his tests were even valid. ****, I averaged over 50mpg with my Cruze over the weekend (DIC said 55mpg), no Trifecta tune, but that was mostly highway driving. I can guarantee you that you won't get a 37% increase by JUST flashing a tune.
A 37% increase is massive in general, but a claim of 37% increase on top of 35.4mpg (which is already high for a non-hybrid) should start raising some eyebrows on even the most avid believers.