Just changed my stock muffler out for the UUC Corsa this last Friday night. The only difficult part is the stupid rubber bushings. I'd recommend disconnecting the bushings and taking them out with the rest of the exhaust before trying to get them off. I used some WD-40 and a small screwdriver to get them started when it was time to remove them.
You can also buy a set of ramps (40 bucks at an auto store) if you don't want to mess with jacking the car up and putting it on stands. That's what I did anyway, was still plenty of space. I would have just put it on stands but I couldn't find a good post on what the best jack point for the rear of the car was.
2009 e92 M3 - AW DCT - Apex Arc8s - Corsa