To the OP, really try to get the bumper painted locally to get an exact paint match. I actually bought OEM Mtech fronts and rears at different times from a reputable vendor and when I bought the rear, the match was PERFECT, when I bought the front it was off by a bit. I ran it like this for 1-2 years, until I accumulated enough rock chips to warrant a respray.
I brought my car to a local paint/body shop that is owned by the local BMW dealer. The paint tech came out to look at my car and said "that front bumper's color is off". He then came back out with 10-15 test panels/shades of sparkling Graphite and explained to me that there are so many inconsistencies in this particular BMW paint color. We went out to the sun and picked the perfect shade of Sparkling Graphite and now my front bumper is perfect.