If you have an ’03 or earlier MINI, you probably have the same vent grilles as GBMINI, with a foam/gauze piece which collects and clings to dirt, insects and everything else that hits it.
Ever since I saw that the ’04 MINIs had an improved vent grille, I have planned to replace mine – but for a long time buying the vent grille meant buying the old part and not the new part.
But finally I have the new vent grilles installed on GBMINI – and they are massively better looking (old on left, new on right):
This is a low cost mod and gives a good looking result; the parts cost me less than $25 at MINI Peabody (including MA tax). The part numbers you need are: 51-13-7-122-505 and 51-13-7-122-506. Make sure you are getting the new design!