Hopefully this will help a few people who are interested in some of the JCW parts for theF56. All this research has been done by myself, so please bear this is mind if you decide to order parts - double check 1st!! For example if you have PDC, you will need different trim pieces to the ones listed.
All prices I have quoted are from the bmwminiparts website and are subject to discount over the BMW / MINI retail prices, so prices may vary and are posted as a guide only.
Part Numbers:
JCW Pro Parts
Individual parts are priced including VAT
51192339038 - JCW Pro larger front splitters - £233.26
51192339047 - JCW Pro rear diffuser (part number also includes larger rear splitters as a package) - £459
51192339041 - JCW Pro spoiler extensions - £?
JCW side skirts:
Individual parts are priced without VAT
51777382181 - JCW primed sill (left) - £86.90
51777382182 - JCW primed sill (right) - £87.17
51777352151 - JCW sill trim lower (left) - £56.49
51777352152 - JCW sill trim lower (right) - £56.49
51777361585 - JCW entrance cover - £40.66 (pair)
Total incl VAT: £393.25
JCW Front Bumper, configured with JCW Pro splitters:
Individual parts are priced without VAT
51777382164 - JCW front bumper primed - £181.55
51777382170 - JCW cover bumper front primed - £38.41
51117360741 - JCW support fog lamp (left) - £13.22
51117360742 - JCW support fog lamp (right) - £13.22
51117360739 - JCW air inlet finisher (left) - £20.72
51117360740 - JCW air inlet finisher (right) - £20.72
51117360738 - JCW grid centre - £26.11
51117365145 - JCW cover fog lamp (left) - £17.04
51117365146 - JCW cover fog lamp (right) - £17.04
51747352343 - JCW air duct brake (left) - £13.63
51747352344 - JCW air duct brake (right) - £13.63
51647360187 - JCW air duct (left) - £13.23
51647360188 - JCW air duct (right) - £13.23
51192339038 - JCW Pro larger front splitters - £194.38
Total incl VAT: £715
JCW Rear Bumper, configured with JCW Pro diffuser:
Individual parts are priced without VAT
51777382173 - JCW rear bumper primed - £173.70
51127382174 - JCW tow eye cover primed - £10.31
51127351655 - JCW grille bumper rear (left) - £9.72
51127351656 - JCW grille bumper rear (right) - £9.72
51192339047 - JCW Pro rear diffuser - £382.50
51127411145 - JCW guide for bumper (left) - £13.93
51127411146 - JCW guide for bumper (right) - £13.93
51127365074 - JCW bracket for bumper (right) - £6.67
Total incl VAT - £743
Part Diagrams:
JCW Pro:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_8985/
JCW Side Skirts:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9311/
JCW Front:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9305/
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9307/
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9546/
JCW Rear:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9309/
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9310/
All prices I have quoted are from the bmwminiparts website and are subject to discount over the BMW / MINI retail prices, so prices may vary and are posted as a guide only.
Part Numbers:
JCW Pro Parts
Individual parts are priced including VAT
51192339038 - JCW Pro larger front splitters - £233.26
51192339047 - JCW Pro rear diffuser (part number also includes larger rear splitters as a package) - £459
51192339041 - JCW Pro spoiler extensions - £?
JCW side skirts:
Individual parts are priced without VAT
51777382181 - JCW primed sill (left) - £86.90
51777382182 - JCW primed sill (right) - £87.17
51777352151 - JCW sill trim lower (left) - £56.49
51777352152 - JCW sill trim lower (right) - £56.49
51777361585 - JCW entrance cover - £40.66 (pair)
Total incl VAT: £393.25
JCW Front Bumper, configured with JCW Pro splitters:
Individual parts are priced without VAT
51777382164 - JCW front bumper primed - £181.55
51777382170 - JCW cover bumper front primed - £38.41
51117360741 - JCW support fog lamp (left) - £13.22
51117360742 - JCW support fog lamp (right) - £13.22
51117360739 - JCW air inlet finisher (left) - £20.72
51117360740 - JCW air inlet finisher (right) - £20.72
51117360738 - JCW grid centre - £26.11
51117365145 - JCW cover fog lamp (left) - £17.04
51117365146 - JCW cover fog lamp (right) - £17.04
51747352343 - JCW air duct brake (left) - £13.63
51747352344 - JCW air duct brake (right) - £13.63
51647360187 - JCW air duct (left) - £13.23
51647360188 - JCW air duct (right) - £13.23
51192339038 - JCW Pro larger front splitters - £194.38
Total incl VAT: £715
JCW Rear Bumper, configured with JCW Pro diffuser:
Individual parts are priced without VAT
51777382173 - JCW rear bumper primed - £173.70
51127382174 - JCW tow eye cover primed - £10.31
51127351655 - JCW grille bumper rear (left) - £9.72
51127351656 - JCW grille bumper rear (right) - £9.72
51192339047 - JCW Pro rear diffuser - £382.50
51127411145 - JCW guide for bumper (left) - £13.93
51127411146 - JCW guide for bumper (right) - £13.93
51127365074 - JCW bracket for bumper (right) - £6.67
Total incl VAT - £743
Part Diagrams:
JCW Pro:

http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_8985/
JCW Side Skirts:

http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9311/
JCW Front:

http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9305/

http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9307/

http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9546/
JCW Rear:

http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9309/

http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B48/ECE/51/51_9310/