Before you replace the speakers, let me give my experience with this a few years ago.
I also wanted what you want - just a bit more hit and low end than it was giving me. I replaced the 6x9s with high end kicker's - not much change at all. I returned them to stock. But I wasn't satisfied that that was ALL there is to it - there had to be something else holding the system back. The Sony system in my 16 Fusion hit A LOT harder than my 15 SHO, and looking at the 6x9 part number - they are the same. At that time I had recently been learning the abilities of Forscan programming - so I started looking at the spreadsheet to see if there was something I could do on the programming side of the audio unit.
Long story short - there was! I can't recall exactly which settings I ended up with - but it involved changing the base vehicle EQ setup in the audio control unit or digital signal processor (I can't remember which one) and I think bypassing the Sony DSP. I guess there's different EQ curves for each vehicle the ACU/DSP is used in, since it is shared between a bunch of models. I programmed each setting on the same song until I found the sound I was looking for. Once I found the right setting, I haven't been disappointed since. It hits just like my fusion did. There really is a lot more power available if you find the right settings to change in Forscan and "trick" the module to thinking it is in a different cabin space.
I apologize for not keeping notes on what I did - but I'm sure if you get over to the forscan taurus forum you can find the spreadsheet and what to change in the audio control unit and digital signal processor. Just one word of caution - BACKUP your original settings before you change anything so that you can fall back if you change something you shouldn't. Ask me how I know