im not sure what the cost of the challenge bar is, but if your looking for something that is more bang for the buck might look into VS Motorsports, I purchasing there half cage and it is def worth it.
BMW E92 M3
EVOLVE Stage II | EVOLVE X-Pipe | EVOLVE E-Tronic Exhaust
Macht Schnell Stage II intake | KW V3 | Volk TE37SL | BMW Performance Spoiler
Apex Stud Kit