Upgrade audio in 2015 Silverado regular cab

[Hult]

As of right now, I installed the 6x9" Kicker 40CS6934 in both of my doors last year.

The quality is a bit better than stock, but still not as great as I intended them to be.

 

I'd like to install an amp this week. And potentially replace the tweeters, and the rear speakers in the pillars along with running wires for a future sub install.

This is the most helpful post I've found so far with the speaker install.

 

Has anyone installed tweeters? Is it actually worth the hassle of replacing them?

Also, should I be running new wires to the OEM head unit? Or should the stock wires be sufficient.

 

The door speakers are 6x9" and the rears are 4x6". Any suggestions on which speakers to buy for the rears?

My buddy is giving me his old amp, going to use that for now then upgrade that in the future as well..