There is a pulley available for the R53 which people refer to an aircon “delete” which is an idler pulley
It is possible to install a gates 6PK843 belt while totally removing the aircon pump, Some may argue that the charger will slip with reduced surface area contact however, two cammed cars running %17 are running this belt with no signs of any slip. This is a cheap way to delete or remove the aircon system from your R53 R52 mini cooper s.
Remove the gas from the system responsibly
Whip the old belt off
Remove the aircon pump, aircon rad and pipework
Install the shorter belt
This photo is not mine, but it was saved on my phone i am unsure what the source is but for reference of the belt path
Alternatively if you want an idler pulley the FEBI BILSTEIN part number is 100099 but do your own research.
