Read this log
https://www.bimmerworld.com/About-Us...-Sport-Brakes/
As I see in some of your posts you have a 335i then you have standard 340 brakes up front. To add the 345 rear they are the same on all models abit some part number changes m235 - m3/m4.
Performance gains won't be huge but it's will look better and pads can be swapped out much faster. After everything said and done you would spend 500+ on rear calipers, then 300+ on rear rotors then powder coat you are looking about 1k would be my guess.
Good luck!
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2020 - M340i RWD | Executive
(Retired 2015 - 335i RWD A8 | MP LSD, BM3, MP Exhaust, M Sport Conversion, 245/35/18 square, VRSF Chargepipe, Rear Brembo upgrade)
(Retired - 2010 328i)
(Retired - 1987 325i Vert)