Actually Dave,I have found how to correctly adjust the speed of the program so it can be calibrated on OT2.OT2 does not use IBO,it uses cam style so when you get your exact speed,slide the performance scale down on the setup page(I believe) and then click over to the spine page untill you get it to show the correct speed for your setup.IT IS A PAIN but this is the correct way to calibrate it.It doesn't show the speed change when you do it on the same page,you must click over before it sets it.
Have you found that to be true all the time?
TFOX is 100% correct about this and I have found it to be true all the time and with different arrows. I have found that the performance slider is like a "setting" for a particular bow model. Once you have measured the speed of an arrow through a chrono and adjusted the performance slider to get the correct calculated speed there will be a value in the performance slider that you can use for that bow model on any future calcs. I have two identical bows except for DW, one is 60# and one is 70# and the same performance slider number works with both (-85). Kudos to TFOX for figuring that out!