I have been looking at lift kits and been doing some math (dangerous!). I can see that it would be required to lengthen the lower control arm or shorten the upper control arm to correct any caster caused by the lift.

I noticed that many lift kits provide un-adjustable control arms. Are these new control arms just stronger or do they adjust for the change in angle?

I have also noticed that some high end lift kits provide upper and lower adjustable control arms. Why both? Isn't having one adjustable enough? Or am I missing some other function they perform?

I am trying to figure out the difference between buying an ultimate kit or buying an economy kit and one set of adjustable arms.

Thanks for the help.