The factory speakers in the MG4 Xpower do produce a descent-ish sound, but I find the sound muddy and the speakers inadequate, especially at higher volumes.
The stock speakers are 25W and become uncomfortable when doing 70mph. The speakers are moulded and glued into the mount, so it's all in one. I couldn't see any after market mounts that I was comfortable buying, so I found a model here and printed my own using ABS+ filament from Amazon. 1kg will manage it if nothing goes wrong. Obviously it did, so ended up having to buy a 2nd spool. I did have to drill my own holes and melt some brass screw cuffs into the adaptor as the 4 holes in the model didn't align with these speakers.
I did price them for a 3rd party to print them, but that was going to cost well over £720.
I bought 2 pair of JBL Stage2 65CF which are 90W RMS at a good price from Amazon.

The thick cuff is from AliExpress. It maybe too thick as the door cards were "interesting" to get seated at the bottom of the door.

This is what they look like when put together:

Took the door cards off and remove the old speakers. I didn't want to cut the original wires, so I purchased these connectors from AliExpress

Also got some sound deadening mats, so they went under the speaker mounts and wires to reduce any vibrations. I did do more, but unfortunately I didn't take any more pictures.

After putting everything back together, it was time to test. I have to say, the sound is instantly clearer with much better bass. So all in all, I'm very pleased with the result. I haven't replaced the tweeters yet, so an update maybe on the cards. Watch this space.