I had the LIngenfelter kit on my '02. It is a straighforward kit, as they explained it to me when I ordered it, 'It's really simple to install the second time you do it. But read the directions carefully and think it through and you'll do well. The kit has hardware to relocate the shock mounting slightly, which you need because otherwise you still can't run wheels wider than 11 inches (I ran 345 x 18 drag radials on 13 inch wide wheels).
While you working on the rear and under the car you might also look at Lingen's rear battery relocation kit. Nicely improves balance and easy to do at the same time.