Update on the coilover kits:
These kits are currently no longer available for purchase and have been discontinued since 2010. We sold out of them back in 2011. The coilovers are fox 2.0 x 6.5" travel emulsion shocks. You can use either the Resi or Emulsion version.
We can have another run of them made if the demand is there, but this requires 20 bracket kits to be ordered for one run ($225 for just the brackets and hardware). The Coil Overs, limit straps, brake lines, tabs, steering stop extensions, and strap clevises if desired are all sold separately.
Logan has already answered a lot of your questions (thanks, Logan!), but just to back it up:
The brackets work on a stock setup or Superlift suspension because the brackets bolt/weld onto the stock lower arm and stock upper shock mount. The overall length of the coil-over changes to accommodate the lift kit, because Superlift drops the lower arms down and increases the gap between the lower arm and the frame mounts.
The kit was intended for ride quality and can be adjusted (like a torsion bar) with the use of spanner wrenches to gain up to 1" to 2" of lift without sacrificing ride.
4WD's need to be careful how much they adjust. If increased too much it will cause the CV's to run at a high angle and fail in a short amount of time. Also, the wheel travel alone can cause CV axles to fail if not properly installed with the limit straps where they need to be. We recommend measuring from either the center of the front hub to the fender lip before and after. Or, alternatively, measure from the top of the tire to the fender before and after, as long as the tires aren't changing in the process. Be sure to "jounce" the suspension before measuring both times.
RCV Axles makes a VERY nice set of custom CV axles for around $2000 to $2200 for the pair that will handle a little more angle than stock, and are WAY stronger (Chevy IFS axles are rated up to a 47" tire). When installing this coilover conversion and RCV axles together, it is entirely up to the installer to make sure the CV shaft clears the lower coilover mount. This is due to a larger diameter shaft supplied by RCV. These are very good choice for the L/T 4wd guys.
Details on IFS Axles:
If anyone has any more questions, they can be directed to either me or John at Off Road Warehouse directly.