I wish I had some first hand experience with the Rustys and SL kits to really see the difference since there's been a few discrepancies posted by members that I haven't been able to verify. If I was to order today, i'd lean towards the Rustys. (if you're around central NJ, let me know... i may be able to help out with the install and get a close up look at the kit..).

For the coilovers, I know JBA is working with Fox on developing theirs. So i'd see how that turns out. KING also lists a coilover P/N for the WK (which should work for the XK) in their new catalog. If they're not listed for sale by mid summer i'm planning on contacting them to see what their plans are. They have a rear shock option too that would work well with their coilovers once released. I would stay away from the 7100's.... Bilstein has been concerning me lately in the quality department.

Another option i'm looking at for rear shocks are the Rancho 9000's. They have a rear shock that'll work perfect for our XK's with a 4" lift. The 9000s are also adjustable so I think that would really help for dialing them in for the perfect ride in combination with a set of Fox or King Coilovers (depending on what types of shocks they may offer).

The HD UCA's by JBA are a "must have". At the first sign that my upper balljoints are going, i'll be ordering their UCA's as my replacement, not questions asked. I think i have persuaded them to consider some tie-rod upgrades for us as well.... not a definite yet, but if they do make them that would be a really good idea if you plan on offroading.

It wouldnt hurt to get the SL or Rustys now, and then add the other parts as the stock items wear...