I'll tell ya right up front. My car started life as a non-sport 2003 530i. After 145,000 miles she cornered like a 1950's Buick. The srings and shocks were changed which did help a lot. She just needed a bit less roll in the corners.
So the options were Dinan, Eibach and someone else... Doesn't really matter who. They were all in excess of $450+ for their kits. Definatly that $$$ is not in the budget this close to X-Mas.
The rear M5 sway bar with new brakets bolts and bushing set me back $130 at the dealer. The bar looks to be at least 4mm thicker than the stock 530 bar.
I or anyone else will NOT take ANY responsibility if you screw up your car when following these directions in this easy DIY.
You will need:
1- To be sober, definatly sober.
2- an alignment when finished is recommended
3- good hydraulic jack ( or ramps )
4- 16mm cresent wrech
5- 16mm or 3/8 socket wrench
6- 13mm socket wrench
7- 13mm cresent wrench
8- jack stands ( if using jack )
9- wheel chucks
10- creeper ( not nessary but very useful )
11- M5 sway bar ( part# 33 55 2 229 136 ) and appropriate rubber bushings
12- Bently manual for added security
13- small needle nose plyers

Place wheel chucks around front wheels.

Jack up the car as the Bentley manual says, but doesn't say how. I used the differential which is not the correct place, but no one could say where the appropriate place was. I used an old thick towel to soften the jack. Ramps may be a viable alternative.

Place jack stands under jack pads. Pads are directly in front of rear wheels.
Lower car slowly onto stands. Be sure they are correctly on the pads. BE CAREFUL!!!
Here is the sway bar. It should look very similar to the new one. Visually compare them before unbolting anything.

Use 13mm wrench & 13 socket wrech the loosen / remove this bolt first.
The top of the braket is held in place via a tongue and groove system. Leave the bushings on the bar. Don not move / remove bushings from the bar. You will see why later.


Use 16mm socket and 16mm cresent wrench to rmove the sway bar link bolt.


Ah ha, the Bently manual doesn't tell you this! Place the cresent wrench as shown in the pic. It's hard to even see in person. The backside of the bolt has 2 flat spots to keep it from spinning.

All the nut & bolts undone. Time to wiggle to old sway bar from it's home.

The old & new.

Place new bushings in the same spot on the new bar, as they were located on the old bar.

Reassemble by following the steps in reverse.
Oh, the small needle nose plyers. If by some chance the sway bar link boots came off while using your 16mm cresent wrench, use the plyers to pop the boots back into place. It is hard to see, but the boot is held in place with a nipple and small rubber band system. Do not leave the link exposed.
Fin.

Good Luck.
Now if someone is daring enough to try. There seems to be 2 different M package FRONT sway bars for the 6 cylinders, which can't use the M5 front sway. They seem to differ in size only. Here's the link for part numbers if you would like to give it a go http://www.realoem.com/bmw/showparts...57&hg=31&fg=10 It looks to be a jump in size from the standard 22.5mm to 24mm & 25mm.