I hate to say it but it looks like they may have played with the correction factor given the way that the two torque curves are presented. He could have been running pig rich but even still ...
Normally the correction factor is controlled by the atmospheric sensor and is typically somewhere in the range of 0.95 (scale output down 5%) to 1.05 (scale output up 5%), however the operator can override this and some tuners play with the value to make them look like rock stars.
I think a stock car is around 255-260 whp on a Mustang dyno and with that level of simple bolt on mods I would expect around 270-275 after tune.
Bottom line, if the OP really picked up 55hp then that should be very noticeable in the old butt dyno, so it is up to him to decide how much was smoke and how much was real.
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