The front speakers were easy enough as they can be accessed under the dash and come out pretty easy but not nice lying upside down In the footwell to get at them. You need to be flexible lol .
The rears are harder as it depends on the condition of the rear speaker panels. Mine were not In good condition so I didn't mind cutting the vinyl overlap on the fibreglass lip as I was getting them recovered . But if yours are good you ll need to gently heat up the vinyl under the door seal to soften the glue and peel it back gently to not rip it. Then there s 3 or 4 small screws Holding it in 2 or 3 at the bottom underneath the armrest bolster and one usually at the top . It ll pop off then . The rear speaker is easily got to then.
I went with dgo speakers original size but Modern ones which will be more than good enough for my audio needs
The retro sound radio is definitely very nice have that on my wish list
Shane