On the K&N filter, I've been running it with no issues on the B58. The issues reported for the diesel B57 (seems to be the MAS getting toasted due to over-oiling the filter) don't apply to the petrol B58. The Supra guys with the B58 seem to use the K&N frequently. and I haven't seen any reports of problems on those forums, same for the BMW B58 forums (I don't see any reported problems).BACKGROUND
The Table lists possible third-party suppliers of air filters for the INEOS Grenadier B57 Diesel Motor (the air filter is also used on the B58 NEEDS CONFRIMATION).
When in doubt use the INEOS air filter. The INEOS filter is 68mm thick. The 68mm includes the rubber/silicone seal on the top of the filter. Some other BMW air filters are the same shape but a different thickness.
AIR FILTER (ENGINE BAY)
BRAND PART NO: MADE IN/COMMENT INEOS GRA-3B02-008230
OEM EI-0000008230Air filter made in Romania, by Mahle. Images here thanks to @Tinki K&N FILTERS There has been issues with K&N filter being used on BMW motors, for example here. Therefore, I will not list a K&N filter part number. MAHLE LX3985/1 Thanks to @ninetubes here. Air filter made in Romania. RYCO Do not buy it. Not compatible with the Grenadier. See review below. Made in Bulgaria. WESFIL WA5440 Do not buy it. The air filter is only 58mm thick, whereas the OEM filter is 68mm thick. I can only go on website descriptions say, and they are saying 58mm. WIX WA10422
CABIN AIR FILTER
Given how often I need to change filters due to dust, the ability to clean and re-use the K&N filter is a big bonus. I did not switch to it for performance gains (as I doubt there are any), rather just for the ability to re-use.