Warning: If you are not competent or do not feel comfortable doing any of these modifications or procedures, then please do not do so. I will not be held responsible for any damages caused by a result of your actions. Now on to the fun stuff!

Parts:
Required
Rear Trailing Arm Bushings x2 (Part Number 33 32 2 228 153)
note: These are the later 96+ M3 spec'd bushings. They worked fine for me.

Optional
Reinforcers (available from Ground Control)
note: The reinforcers I am installing are NOT from Ground Control

Rear Trailing Arm Bushings

Reinforcer Plates

Equipment:
Jack and stands
Various Sockets and Wrenches (by memory 10mm, 13mm, 16mm, 17mm, and 18mm)
Impact or Cheater Bar and some muscle (trust me, it'll be worth it)
Hammer
Sawzall
Drill with large drill bit
Pry Bar
Chisel
Torque Wrench
Some sort of press mechanism (the parts I used are listed below and will be shown later)
Gear puller
large piece of strong thick metal


Air tools always help ease removal and installation

Procedure:
I did the first one in about 2 hours working slowly and documenting with pictures and what not. The second took just under an hour.

1) Raise vehicle, properly support vehicle, and remove rear wheels.
2) Support rear suspension with jack and remove lower shock bolt.

3) Lower suspension, but do not allow to hang free (may cause CV joint damage) and remove the brake line bracket from the backside of the trailing arm.

4) Make position of trailing arm cup with white out, permanent marker, or white grease pencil.
5) Remove three bolts securing cup.
This may take a lot of torque alignment shops usually use an impact on these. So get the impact out and go at it. No impact or a weak impact? Get the biggest wrench bar you can find and pray it doesn't break with that monster cheater bar. If it does, get a 1/2" wrench. Below are a few pictures of the carnage...

Below are a few pictures of the deflection without the reinforcers.
Granted this isn't how they deflect to change toe, but it shows just how much they can move.

6) Remove bolt securing cup to bushing and pull off the cup.
Easier said than done. This is really a pain. Try wedging a wrench against the fender well and cranking away with an impact or wrench on the other side.

7) Note the position of the bushing so the new one may be installed in the same way.
8) Drill throught the rubber part of the bushing so that the sawzall blade will fit through the hole.
I made 4 holes so I could just go from hole to hole with the sawzall. It's not very hard with a good drill.

9) Use the sawzall to cut the center metal piece out of the bushing and remove. (don't forget these will get VERY hot)

10) Cut into the remaining bushing towards the trailing arm until you get to the trailing arm. Be careful not to cut into the trailing arm though. Make 2 cuts and remove the piece with the chisel and/or pry bar. Pop the bushing out.

11) Take the new bushing and set it into the trailing arm in the same orientation as the old bushing with the hammer.
12) Use the press mechanism to draw the bushing into the trailing arm. Be sure the bushing is drawing straight and evenly. Be sure you press it in the same amount as the old bushing.

13) If you have the reinforcers lay them into the cup and slide it over the bushing. You may need to tap it on with the hammer.

14) Slide the bolt back in and tighten it down to 81 ft-lb.
15) Bolt the cup back to the body and align to the marks as best as you can. Tighten to 57 ft-lb. That seems a little low to me so I cranked on them a bit more (don't blame me if you break something).
16) Check to be sure the spring is seated and raise the suspension up. Replace the shock bolt and torque to 57 ft-lb.
17) Lower the suspension back down and replace the wheel. Torque to ~78 ft-lb once it's back on the ground.
18) Repeat for the other side.
19) Get an alignment.

Update [04.01.03]: I installed the summer wheels/tires today and I can say that the new RTABs and enforcers really make a difference. The rear end is really locked down now, no more wiggle on accelerating, or strange tracking and sloopiness around the corners. More comments after I get to drive it a bit more.

Update [09.21.03]: After one track day and one autox this summer I am confident to say that I'm thrilled with this setup. The rear end is locked in very nicely and on the street there is no extra NVH. Gone is the unpredictable rear end wiggle and funky handling. If you're having strange rear end problems and haven't changed these in 40-60,000 miles I'd put them near the top of the list of things to fix.