I want to drop my truck but I am confused at what the kits mean by with or without air suspension. i don't have the up and down air suspension, but I do have the auto level in the rear. i can hear it when it comes down off the jack. I was looking at the S2 by BG or the HR's. Which are better and do I need the with or with out kit. I have an 02' 4.4i with 30mm spacers in the rear if that makes a diff.