if the e92 M3 is similar to my e90 sway bar install it looks a little frigthening looking at the stuff that needs to be removed to include the exhaust etc.
One tuner shop gave me a 4 hr labor cost for my e90 325i. but with some local gas station mechanic ingenuity he was able to do it in 2 hrs.
If the M3 is similar in desggn, this job most likely involves dropping the subframe. but the trick to all this was dropping the frame by loosening 4 long frame attachment bolts. Keeping it still connected to the car upper body frame is the key and just loosening the bolts out at about 3 inches. Eniough to get some wiggle roon to maneuver the sway bar out.
BUT STILL ATTACHED TO THE CAR.
Once about three inches in dropped, you can then remove the rear wheels and slighty get the rotors out of the way. So you can feed the sway bar out and in from the wheel wells. (after of crse loosening the mount clamps.
Thats how it was done on my e90. but for safety, the car has to be jacked up on the lift using the 4 point frame method, leaving the rear wheel axle hanging BUT supported by another aligator jack at the rear differential case unit.