Door pods

I think it will affect sound quality if you make the sealed door pods too small.  Especially if you expect to get midbass out of the pods.  If, however, they are true -midrange- speakers and aren't being used to play midbass frequencies the air volume will matter less. 

From MB Quart:   "All of MB Quart’s midrange/midbass speakers are optimized for infinite baffle/free air mounting, which is essentially mounting in the door or factory speaker locations. They will work best in this type of mounting using the door cavity as the enclosure. Sealed enclosures are not recommended since they would require larger than practical volumes for the speaker to function optimally. This holds true for all MB Quart products with the exception of our subwoofers. If a midrange/midbass driver is put into a small sealed enclosure, it will alter the speaker’s response characteristics and you will not get the full amount of bass or midbass that the speaker is capable of producing."