Does the speedometer affect performance?

[02roushstg3]

My buddy installed gears in his car and hasent adjusted the speedometer yet. He did order a speed cal but its not in yet. Does the computer use the speedometer to adjust any settings in the computer for performance? He wants to take the car to the track this week but wasnt sure if the speedometer being off would hinder performance. Any thoughts? PS. Car is a 03 gt.

 

[XTONKAX]

I want to say yes, but don't have any proof that it does. He'll be fine until he puts the SpeedCal in, though. I know that when I had a problem where my SpeedCal didn't have power, the car would stall out a lot more when stopping. I'm guessing the computer didn't sense the speed so the IAC said, "Hey, let's kill your revs!" Just guessing, though.