It seems this car was making above the factory stated HP from the start.
Its not appropriate to assume this until you know more about your tuners dyno. Is the dyno generally "high" or "low". Typically a dynos most valuable test is before and after gains from modifications...there not all calibrated to be identical....4% between dynos for 600rwhp is 25rwhp difference..thats very realistic.
We all like to hear great things about our motor & car but whats more improtant is knowing the truth and thats done by getting more data and applying a proper trending process.
Also please keep the same scale, not good to bounce from "uncorrected " & "corrected".
Its probably best to benchmark your dyno test with other vipers and stock performance cars dynoed on your tuners dyno. then compare these sets to what posts for identical cars measured on other dynos.
I think more than on VCA guy was trending dyno hp, mods, and dyno machine type.