Which dyno run went first? The uncoated interior or the coated interior? Engine temperature on one of the runs was most likely hotter.

My friend just had his GTO dynotuned. They made a stock dyno as soon as he got there after an hour drive. Then they reprogramed the car and ran another dyno. It said he gained 44 HP with a tune only. Well, they say it was more likely a 35HP difference, the extra 10HP was due to the cooler engine temperature on the second run. My point, there's a lot of variables that could affect it, slightly different temps, collectors, primary widths...etc.