Andy - Thanks for clearing that up for me - Can you tell I'm a complete novice?
1 more question if I may, as you seem to know what your talkign about.
Will I get a better sound with good bass by keepng the original tweeter in use and opting for a mid/bass driver replacement only - OR - go for a 2 way like the Infinity and disconnect the standard tweeter?
Am I right in assuming that a good mid/bass driver and a seperate tweeter will sound better than a 2 way that does both?
no problem mate.
i think this all depends on your personal preference, if you want better 'sound staging', then i'd be more inclined to keep the original tweeter and just replace the 6.5 inch mid/mid bass driver for a better quality unit such as the phonocar in the link.
plus, you'd be better off using some sound deadening material, such as dynamat to reduce vibration through the door card, as the mid bass driver is screwed to the door card, not the inner metal skin of the door.
the whole idea of the component set up (a seperate tweeter and mid/mid bass) is to give a better sound reproduction by having different sounds coming from different points.
with a 2-way or 3-way in the bottom of the door, the high end and low end sounds are coming from the same point and will sound different.
go and have a play in a decent car hi-fi shop with a 2 or 3-way speaker set up, and a component set up and see which sounds better to you