This service bulletin is from Butler * Smith about how to safely remove the exhaust nuts on your BMW motorcycle. It is very poorly written too as we came to expect. I highly suggest making two saw cuts about 180 degrees from each other, then use a chisel to split it.
I suggest that if a bike is new to your garage, consider this action. Back off the nut, if it doesn’t come off easily, then cut it off. Once off, grease it up really well and put it back on. Do not torque it up to the BMW spec, as that greatly increases the chance that it will gall. Tighten it a bit, start the engine and only tighten it enough to stop the audible leak. You may find that you are only at 1/3 the recommended torque. Now you can be fairly confident that if some issue happens out on a ride, or anywhere away from tools, you can remove the exhaust nuts without risk.
If you plan to keep this motorcycle, consider buying and storing a spare exhaust nut. They are cheap and it may come in handy. To learn more about exhaust nuts, click here.