so, I got into a minor accident this morning - rear bumber is cracked. I have a 2001 530ia - trying to figure out if I am better off with replacing with the stock 530 bumper or use this as an opportuniy to install the 540 sport rear bumper. Would the stock 530 exhaust look weird witht he 540 sport rear bumper? what do you guys think?

time to body kit?

umm buy the cheapest option and save the money for future troubles as you'll have many (mostly electrical)

Great excuse to upgrade. Go for it.