Z28Fanatic

I recently purchased a UMI tunnel brace mounted torque arm, and it comes with a bracket that allows you to choose between two different mount positions for the front of the TA, which they say adjusts the instant center of the vehicle. The lower mount point makes the TA sit more horizontal, whereas the upper mount raises the front of the arm slightly. What would be the advantage of being able to do this? What would an optimum setting for this be in a car such as mine? My dyno numbers are in my sig and the car weighs approximately 3600 with me in it... I will be running slicks and skinnies on my next track visit, ride height is stock and I dont have any drag-specific shocks, just the Bilsteins that SLP puts on the cars. Sorry if this seems like a noob question... I've never messed with an adjustable suspension component such as this before.