Disco 2 Can I use 4" speakers in the upper door position?

I'm looking at refreshing my speakers, and I've got some really nice sounding 4" speakers that I would like to use in the upper door position, but AFIK the standard speaker size is 3". I don't want to butcher the door cards, so if I am going to install them, it'd have to be inside the door card rather than screwed to the door card. So I was wondering if anyone knew if it was possible to fit 4" speakers in this location?