Super interested in the X5M bumper conversion. I was seriously looking into doing that myself.
I don't think any cutting is necessary, you just get the front M fender flares and the M bumper, and it should come together. The only reason I backed-off from doing it was my body shop guy was saying we likely needed all the M ducts, bumper support, etc. Price with parts and labor was going to be about $4,500.
But again, it may be a lot easier than he thought and you may not need all the parts he listed on my estimate.
Some other guy did this conversion in England.
http://www.xoutpost.com/bmw-sav-foru...it-wheels.html