One of the easiest and best ways to upgrade the breathing abilities of the F2x N55-powered M135i / M235i is with a replacement performance panel air filter.
We've developed our own range of MMR performance cotton gauze filters that easily drop into the OE airbox which provide excellent filtration properties, combined with instant performance increases and induction noise enhancements.
Having dealt with MMR numerous time I knew their filters would be second to none. Fantastic quality and fitment. Highly recommended!
Great company to deal with. The filter looks good quality, my only comments would be to include a do not throw away sticker explaining it is a washable filter to go on the air box and also I would expect some sort of guidance on maintaining the filter. Great to have the option for oiled or dry filter.