I just finished installing my new tunnel mounted umi torque arm tonight and I am pretty impressed. I did not notice any ill effects over stock other than slightly more vibration which I can understand. The question I have is, which angle is positive and which angle is negative. Right now I have a total angle of about 1-1.5 degrees between the rearend and the driveshaft. That is, if the rearend is at 0, the front of the driveshaft is pointing down.
Is this negative or positive?
I hear the best setting is around 1-2 degrees negative? Am I already there or am I on the opposite side of things?

 

If your calculations are correct, and you were reading the angle finder the right way, you got it. The only reason I mention this is because I screwed it up the first time trying to read the angle finder.

 

The nose, front of the diff should be down relative to the driveshaft by just a degree or two- under heavy acceleration, it will torque up slightly and be in-line-

Easy to adjust on ramps, you can experiment a little and tune it- it really depends on how hard you are accelerating, versus how much time you spend cruising- Took me a couple tries to get mine dialed in right. Nice to not be putting that load into the tail end of the tranny, too-