The Doors are a little more complicated.
Originally, with the 4 channel Amplifier upgrade, the doors are supposed to contain 5.25" 'sub-woofers' in plastic enclosures:
I managed to get hold of a guy on Renntech who made some custom enclosures from fibreglass and MDF by using an original enclosure as a mould, so I bought a pair and then thoroughly coated them in liquid dynamat and sheet noisekiller.
and then the insides were loosely packed with acoustic wadding -
which males the speaker sound like it's in a slightly bigger box, adding a little 'punch'
As you can see here, one of the advantages of the Infinity Kappa speaker is the tweeter on a pivot and +/- 3dB switch:
and finally fitted back in the door:
