Im not sure about Prior Design. I live near there location in LA, I suggest u should ask if they have installation fercilities. If not just screw it.
My conclusion now is:
M6 conversion OEM genuine kits
Hamann (wing for e64)
Vorsteiner (fron splitter and rear diffuser)
Hamann diffuser wont fit my oval tips so i think i'll go with vorsteiner. The hamann wing looks great, but I prefer get it matte black or wrap carbon than exterior color match. Because it will mess the combination of CF from Vorsteiner.
2009 BMW 650i Cabrio (daily drive)
2011 Audi A4 (groceries, bully, road trip, winter beater, family car)
BMW CCA ID: 473647