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You will need the adjustable UCA if you have lowered your car to adjust the pinion angle to specs. The LCA definitely help with wheel hop and launching.
Convince me why this is an important mod to compliment lowering springs..
They (UCA and LCAs) can be treated as separate mods, and the best technical reason for doing either of them is if the car isn't doing something that you want it to or does something (like wheel hop) that you don't. You'd do either or possibly both along with or shortly after lowering if the car's behavior worsens.
Since control arms can be done as separate mods (there is no need to remove the springs or shocks in order to do them), my thought is to first lower it and drive around that way. Find out if you have any problem that LCAs or a UCA would fix, and go from there. If no problem surfaces for you in your individual driving, you're done as far as the mechanical reasons are concerned.