Took the advice and bought some new Sony 2 way speakers, yes just removed 3 of the tabs and used one tab left to screw down and stop them moving.
Sound now drastically improved from the standard speakers, the one that was rattling had disintegrated around the cone.
don't know if I'll bother with the door units yet, will give it a go with just the new speakers first.
Still thinking of what do do re the head unit as I'd really like apple car play at least.
The old stereo budget rule is spend 50% of the budget on the speakers.
Generally, the bigger the speaker magnet is, the better they are, as they are more efficient at converting the electricity into audible volume, without the need for extra amplifiers.
Little expensive speakers with large magnets can out perform cheaper larger speakers with smaller magnets.
The foam ring that supports the speaker cone is usually the first item that deteriorates and fall apart.
They can be replaced at a fraction of the cost of a new speaker, however, if it is a cheap crappy speaker, just buy a new better speaker.