Sound upgrade on base F30

Hi guys.

Hope you all are well.

I am looking to upgrade the sound on my base model 2013 F30.

From what I read and someone can confirm the car has:
4 X 4inch speakers on doors
2 X 6 inch speakers under the front seats (although housing would accommodate 8inch perfectly?)

My eventual goal is to change all speakers and amplify them. Will also add a small sub.

The thing is I have to do it in stages due to budget...

So as a first step is it better to:
1. Change the speakers and run them unamplified or
2. Install an amp to amplify the current speakers

If I go for option 1 can you guys recommend any brands that you have had experience with.

For the amp I was looking at either a new RF Prime 300.4 or a used RF Punch 400.4.

I just can't believe that BMW let's their vehicles leave the factory with such a crappy sound system even if it is just a base model.

Ps. Car is out of MP so that's not a concern.

Thanks in advance