Thats the one I use. You are correct, it is not adjustable. My car isn't lowered, but the rear suspension compresses completely on hard launches at the strip. My driveshaft hasn't rubbed the loop at any time.
have a 1 piece Alum. there is not gaurentee which end it will break at.
the reason you should have it on the front. If the front breaks it can dig in to the ground and cause the car to flip. But a rear loop is not required until I am a lot faster. I forget how fast maybe 9.99 or faster. I will read more about it later. I know I am good to 10.00 right now. When I add more power and get closer to that E.T. I will know the answer.