out of those two, i assume u mean just the 5100s, not the COs, they state when used with stock springs, up to 2.5 front lift, the rear would then need a small spacer (1.5), since the billies are for a lifted vec. u could use fj springs which will give ya another 1/2 to 1 in. on top of that, then u could skip the spacers, this will be cheaper than the full OME setup, & a good way to go. the OME depends on which coils u order with it, with 884s on front ya get 2.5 & with spacer on top get 3 in., im not sure what the rears give u but the flex coils will give a better street ride. the med. 895 may be a liitle harsh for u. id say if u mostly do street & want a smoother ride, the billes are the way to go. it depends on if u want to keep cost under 850, since that will be around what the OME setup will cost before the install. total for the 5100 + fj coils & rear spacer, around 450 in cost, depending on what u pay for the coils. hope this helps a bit.
