I just finished 90% of the job, so I thought I'd post while my knuckles heal. If you're considering doing the swap yourself, read my notes with the understanding that I'm no pro, but I've done plenty in my garage over the years.
The Strutmasters instructions were on the weak side, especially for the rear. Since I have never done the struts on an LS400 before, I relied on them to get me through the first time. On the list of required tools, they listed a spring compressor as "if applicable" for both front and rear. Tough to plan ahead if the instructions specifically for your car can't be clear.
The fronts went pretty well. No hand-holding in the instructions, but good enough. Puritans should look away for a moment and back yard mechanics continue. With a spring compressor, the bottom of the strut will be easier to bolt in. I used a screwdriver through the mounting hole and into the strut so I could pry it into position. Used my foot to "stretch" the suspension down for the rough positioning. I knocked the bolt through with a mallet, but not so hard that it stripped any threads. A helper would have been nice, but it's possible to do alone. The instructions do not deal with the remaining air line. I just pushed the grommet back in the hole and left the line open--no turning back. They do recommend removing the positioning sensor arm and plug. I did on one side, but it wasn't in the way, so I didn't disconnect them on the second strut. As an aside note, I'd suggest doing the passenger side first. It's more of a pain because it's difficult to reach the air line without removing the air cleaner and associated plumbing. Made the second one seem like a breeze. Time: about 2 1/2 hours, including pulling tools, jack stands, etc.
Working on the rear set is a different story. If you don't know already, you'll be pulling out the rear seat. Not a big deal, really, but I hadn't anticipated that (I always had a truck). Number 1 suggestion--don't start unless you have extra hands available, at least for installation. The instructions do not mention the air lines at all. They are in the trunk, behind and above the gas tank (14mm, before you climb in). The left one is just to the right of the amp. They do recommend removing the caliper, disconnecting the sway bar and position sensor, and removing the rear drive shaft (I'm assuming that means unbolt from the third member). It also mentions loosening the center suspension nut. I have no idea what they're talking about. I removed the caliper and disconnected stuff on one side, but found it a waste of time (YMMV). Again, it is possible to do without a spring compressor, but easier if you have one.
I bled the air, compressed the strut and it came right out because it was short. The new one is fully extended and tricky to put in without compressing. I angled the bottom through the A-arm(?), pressed down on the axle and managed to get the top under the fender. I continued that line of thought--lifting, angling, and twisting--until the top was in its well. Here's where another body saved the day. One of us lifted the strut and the other was in the car lining up the top. We put a socket on the center bolt to help guide and keep fingers out of the way. Once the studs started in, we put the nuts on finger tight. It took some fussing, but we got it lined up and snugged the bolts. The bottom bolt was a similar deal to the fronts. The instructions did provide torque specs, so that was the final step.
I took the car for a ride and it is definitely stiffer. For me, that's a good thing. Not harsh, but similar to my other LS400 without air. The car is noticeably higher, too. I imagine it will settle a bit and it will be just a tad higher than my other car. I did not have the experience of higher in front, but instead it's a little higher in back than front. Time: about 4 hours
Tomorrow, I'll put in the seat and address the electrical. The instructions say to cut certain wires, but I'm going to see if I can just pull the plug on the ECU. Maybe cutting wires is best if you only do front or rear. Meanwhile, I have a blinking "Norm" light.
While not complete, I hope this helps someone with their decision. I've had great advice from this forum and I hope to make someone's job a little easier.
Edit: I looked at the wiring diagram and the wires I was supposed to cut went to the dash LED's for ride height. I simply unplugged the connector they mentioned (closer to the rear of the car on the bottom of the ECU) and I've had no complaints from the wife :).
