Generally with static anything the lower it goes the harsher and farther geometry gets out of wack.
Rear: if the axle is under the leafs, remove it, put it OVER the leafs. That will get you 3.5" (what ever the axle tube dia is). Then you can get a block for another .5,1,2,etc" more. Shackles work the same way. Keep in mind shocks will be “riding” farther up the travel and thats not a good thing, without detail they wont last as long as normal. Lastly, you are closer to the bump stop. If you hit a bump and the suspension travels 5 inches stock, it will travel 5" dropped. If you are 4 inches from bump stop, dropped… you just bottomed out on that bump.
Front: Same concept as above spring wise. Struts/shocks wont last when operating out of their “sweet spot” valving wise. Take in consideration the geometry changes. Changing control arms can change camber, caster, etc. Thats why complete static drop kits have upper/lower control arms, springs and more importantly spindles to get the geometry back in check.
Come tell me that when my shops Duramax express van lays frame, pulling my car trailer with a show car on the back!!!
its a 6klb, 450+hp 800TQ+ pulling machine rolling coal on air ride. (soon)
hows that work?