It's the correction factor the dyno shop used. Alot of shops use STD because it reads higher and makes the customer happier. When compairing the best is SAE. It will lower you power totals a little due to it's harder corretion factor. From what I remember if I used STD #'s I'd pick up another 10 or so hp and tq on my dyno graph.
I believe its what your car actually made on the dyno. SAE puts in correction factors so that everything is even, and is the general accepted way to compare #s so no matter what the weather is and where your at it puts up what the #s would be on a standard day. Or its supposed to...but it can be slightly off.
For example @ MPH my car made 468 SAE and tim said it went over 480 on the STD #s. I just redyoned my car and got 479 SAE after making a few changes...didnt ask about the STD #s though, but I would assume about 10HP up. Your car most likly makes around 500RWHP SAE.
Go back to the shop and have them give you the SAE version....they should still have the file in their PC...they should have both as I think it automatically does both. they just gave you the STD chart because the #s were higher
Actually they have "uncorrected" as another option you can get your print out in's. That's the one that show what you made that day. Depending on the weather and your altitude it could be more or less hp.
Most dyno sheets will show you the correction Factor. You take your corrected HP or toque and divide by this number to get uncorrected numbers. If the number is greater than one (which it will be in most cases) your uncorrected HP will be less. They calculate the correction factor from barometric pressure, temperature and humidity. what formula they use depends on which SAE correction they are using. There is more than one and the use different valve for what is called a standard day.