Must admit, I didn't notice the mistake in the kit. The kit filter is actually the 'factory fit' Vokes filter. The smaller, more compact 'Aboukir' filter fitted to the particular aircraft shown, takes its name from the MU where it was designed and built, in the field, at Aboukir. Apparently, it was actually a better filter overall, working as required, and causing less drag and consequent drop in performance. The 'powers that be', though, suggested it could cause over heating - probably 'their' way of justifying the 'official', large and ugly filter housing !
Tamiya didn't really get it wrong with the filter, just with the particular aircraft. Pity they didn't include an 'Aboukir' filter as an optional part - but then they didn't include the deeper, tropical radiator either, which should be fitted to a MkV 'Trop'!
Seems they just threw in a Vokes filter, different decals, and boxed the standard MkV kit as a MkV 'Trop' !