I was told by Renntech that other companies say they can get you the h.p. to get the you to buy it, but of course that's coming from a company thats trying to make a sell to me. In my opinion it does have to do with being a little conservative to have a reliable and safe product. In the case of the guy that got his car tuned by SI, the car was on a dyno so they could tune it in "just right" for that car. But not all cars are exactly the same from the engine all the way through the drivetrain. In what I read about his tune it was retuned three times to get this out come, so if I was the guy at the magic table and was wanting to make sure I was not putting someone's car at risk and someone sent me a ECU, I would probably do the second remap just to be on the safe side. The only way to tune a car to get all you can out of it is to have it on a dyno to get input from the changes that you have made to see how much farther you can go with the adjustments in the ECU.