[Davisca455]

Disclaimer:
Not a direct M3 repair, but maybe the technique could be helpful to some M3 owners?

Took a ride with my oldest son in his Focus RS.
At 73 mph, something up front started flapping around and made a super annoying noise.

We get home and check it out.
The forward under tray and splitter were all busted up and flinging around.

I was all "Hey, us M3 owners definitely know what's up with that."

The local Ford dealership had both parts in stock, $424 for the forward under tray, $166 for the splitter.
(He wanted to go aluminum aftermarket for the under tray, $630, but they were out of stock, and he still would have had to buy a new splitter. So he was happy he got both OEM parts for a smaller dent in his wallet)

Here's the bit that might be useful for an M3 owner.

Unfortunately the front bumper cover also had a pair of ripped out holes.
I thought it was worth a try to save it with some aluminum backup plates that get epoxy'd into place.

The epoxy'd backer plates saved the bumper cover, and the front of the car is solid now.
He's ready for his first track day!

Lessons learned.
1) Back in to parking spots whenever possible.
2) Even though you can, don't plow snow in your Focus RS.