If were to have lowered springs for my car, would getting an RSB have a noticable difference or not? What brand of lowered springs is better, Eibach or H&R?

 

Lowreing your car with Eibachs or H and Rs will improve the handling of your car. If you install a rear sway bar and fstb your handling will improve a bit more. I have both. I have Eibach springs and a Stillen rear sway bar and the front strut tower brace. My car handles very well

 

Eibachs are little bit more on the stiff side...H&Rs are on the softer side...

Springs+shocks+FSTB+RSB=You're set.

 

You can never go wrong with getting both. Go for it man, you'll love it.
I wish I could lower my car