I can recommend the Focal speakers, were easy to fit and have upgraded the sound nicely.
I managed to source some MDF mounts like these
https://www.ebay.co.uk/itm/ROVER-75-...IAAOSwRgJXhKqu
Not how much difference they made as I did it all at the same time but were more solid that the standard plastic items.
I did all the speakers when I did mine because when I have done this in the past on other vehicles the speakers that were not upgraded ended up spoiling the sound through distortion so were switched off.
Well worth shopping around for the speakers, mine came from overseas and were half the price of buying them here if you can wait a couple of weeks?