Changed mine a while ago for Focal Polyglass units. It's pretty straightforward. The door car needs to come off (obviously) - there's plenty of how to's floating around on how to do this.
Once the card is off, if you have the 10 speaker set up (like me) then the mid bass driver is screwed into the reverse side of the door card and is very easy to remove, replace or upgrade. The Bass speaker remains in the the lower part of the door and is riveted in place (6 rivets if I recall correctly). Drill these out - remembering to remove ALL swarf that may have collected in the bottom of the door to prevent any chance of corrosion later. Speaker then drops off complete with it's mounting baffle and is easily unplugged.
The cross over unit is also bolted to the door just forward of the bass speaker and is hled in place by some quite long torx bolts, but very easy to remove.
The tweeter is obviously mounted in the front mirror plate triangle. Once the door car is off, then triangle can be easily removed. The speaker is glued in place at the back of this plastic trim, and can be easily removed with a kraft knife. If replacing with a new unit, then just use a glue gun to cement the new unit back in place.
TBH, the whole thing is pretty straight forward, and for me at least, the longest time was drilling out the rivets for the bass speaker as my drill bit wasn't exactly sharp. Do take the time whilst the door car is off to add some extra self adhesive sound proofing sheets to the door inners. You will be amazed just how much difference this makes to the bass response even if keeping the stock speakers.
Cheers
Andrew
