My family owns a Axia and all of us complain how muddy its audio sounds thus decided to do a bit of upgrade on the stock audio system

I am sure that some will suggest to change HU first but after much much readings here there especially in Axia thread LYN, decided to remain the stock head unit and change the front stock 4" speaker.
I also read that stock speaker takes in 40 watt and the speaker hole is actually 6.5".

So now we simply want a good simple upgrade over the stock setup, prioritizing on best bang per buck upgrade. Budget maximum is RM300.
With such budget, I believe it is clear that 2 way coaxial is the way to go.

Done some market survey for coaxial speaker online at Xciteaudio & Lazada speaker, there is simply too many brand & type to choose 

Anyhow highlighting some of my findings
Can ICE sifu here recommend any better ones?
And since this just involving replacing out stock speaker, I am thinking to just to DIY and not visiting audio accessories shop 
As far as I know, its should just be unplug the wires and connect to the new speaker. And get spacer rings if the speaker magnet touches the window glass.
Is there anything else I should be aware of?

Summary to recap:
Need recommendation for 2 way coaxial speaker 6.5" under RM300
Thanks guys!

But isnt coaxial also combination of woofer and tweeter? Is there any reason you recommend this DB Drive brand over the rest?