I followed these instructions and it worked for my 2014 535xi m-sport. By the way if you want a set of nice quad tips for your new exhaust check out below links. These look great with the M5 diffuser which I also installed on my 535. (See
http://f10.5post.com/forums/showthread.php?t=812737)
I've had these tips on my car for a few months and seem to have pretty good build quality. I really like the rolled tips, it gives it a more OEM look. I went with the 89mm (3.5"), since I felt the stock M5 tips were slightly small (I think stocks are about 3"). These are $89 each so $180 for both which is expensive however there is no welding necessary which makes it worth it.
By the way you will have to trim the exhaust exit pipe a few inches to stop the tips from sticking beyond the rear bumper, but you can use the exhaust cutters for that.
http://www.quality-tuning.com/audi-a...-l190-200-in60