Suggestions for Sound system mod - phase 1

[JFR1]

I am planning on upgrading factory sound in phases.
First phase are new speakers, parrot bluetooth, powered subwoofer.
Phase 2 - Pioneer Nav/DVD, Metra adaptor, TV Tuner, JL Stealthbox, amp.
Phase I listed below. Use factory head unit.

Can anyone advise how big improvement you get from a speaker upgrade? Comment on chosen speakers?
Phase I
Front Speakers: Infinity Kappa 6.5 2 way - $99
Rear Speakers: Infinity Kappa 6x9 3 way - $119
Powered Sub: Sound Ordinance 8", 120 watts - plan to mount under front seat or in trunk. $200
Bluetooth: Parrot CK3000 $99
Harness/Parrot: $103
Installation: $381.
Total: $1000.

Phase II will add another $1400 for headunit and $200 metra adaptor.
Thanks
JFR!