The main difference that I noticed between the P7 speakers that I purchased and my original Hi-Fi setup are the following:

1) my original hi-fi setup speakers are 4ohm and put out 25watts and the subs are also 4ohm that put out 40watts, while the p7 speakers that I bought are 2ohm and put out 40watts, and 2 ohm 70watts for the subs.

2) my original hi-fi setup has the in trunk amp(2x40watts) which only amplifies the subs underneath the front seats, the midrange speakers are directly amplified from the ccc unit. While the P7 setup has all the 7 speakers + subs amplified from the bigger p7 amp (also located in the trunk)

I added the rear door speakers (which where non existent in my original setup) as well as the center speaker. I did not swap out my remaining original speakers yet, I am waiting to find a P7 amp at a decent price, and finish my install.