shackles get you 1/2 the increase length so if your shackles are 2 1/2" longer than stock (4") then you get 1 1/4" lift. yes shackles this long are a detrament on the trail. just changing the spring pertase from the bottom to the top will net you and average of 5 1/2" of lift, plus your 4" spring and you've got 9 1/2"! good luck with that driveshaft on that one
I would recomend removing the shackles and changing fender flares to regain your clearance (TJ's, tube, warn cut outs, zenons, ect.)
Sold) 94 YJ, 4.0L 5 sp manual, Hard top, 33/12.50s, 4.10 ring&pinions, Polished D30 w/Aussie front, 8.8 rear w/ LS, 2.5" RC, 2" BL, 5/8" booms, TJ flares, SYE, custom F/R bumpers and rock sliders, 8k winch, dual optimas, HO alt.
2) (Sold) 99 TJ, mustang 5.0 GT 40, AX15/231J, trektop, 37x12.50r17 cooper STT, superlift 6" long arm, D30/44 w/ ARBs & yukons, customized warn bumpers, custom sliders, 12K winch w/ synthetic rope, custom paint
3) 2007 JKU being built now