Louder speakers for stock HU

[butterMilk 10+ year member]

So i have stock rockford sound system in my car, and it sounds good. Supposedly a 650w system, and has a sub in the trunk. But it just doesn't quite go loud enough for me. I would like to get some quality new speakers, that hopefully play louder.

If i get speakers that have a higher sensitivity would that help? (95 db)??

Or speakers that have a 2 ohm rating would they be able to draw more power, and be louder?

There is a amp under my seat, so i think the speakers are running off a amp. Probably not much power, but I'm hoping just enough!

Any recommendations for something that might work for me, i would like to keep the stock HU. If i get some good speakers and it doesn't get any louder, then i will get a aftermarket HU.

Oh yeah there component type speakers,6 inch, not sure if theres a crossover in there somewhere. Want to upgrade to 6.5 inch

Just found this info...

2x 1" Tweeter (Soft Dome)

2x 6" Midbass (PP Cone) 25Wattz - 4ohm

2x 6" Full Range 2-Way (PP Cone) 25Wattz - 4ohm

1x 10" Long Throw Subwoofer

8ch DSP Amplifer 650W (Max)

Click to read more...