I ordered the diffuser direct from Seibon for $580 plus $150 shipping. It doesn't fit. There's a gap on either side.
Waiting to hear from them about what they want to do.
2014 X5 xDrive50i ZMP - Alpine White/Mocha (On Order)
2013 Tesla Model S P85+ - Gray/Black (Sold)
2013 F10 M5 (Sold)
2013 Cirrus SR22T