I think you will be more than pleased if you replace the head unit and then decide if you want more.
You would be amplifying a stock signal. In the end you will be getting more bang for your buck from a cleaner signal rather that amplifying a stock radios ok at best signal. You are allready on two car threads that we know of.
Most likely you are or will be inclined to do more.
This is just my opinion.

Iv got jl 6.5s in my doors and 6x9 type s in the rear and they are very clean and loud

I have the Kenwood's and they work very nicely.

polk actually makes good amps. The sound quality is alot better than most.

$150 for a 2 channel that does 75 @ 4 ohms, Thats stupid, you can get a 4 channel on sonic that would do that or more for the same price and only use a pair of channels, then if you decide to upgrade use the other 2 for more speakers....

The polks run very clean signals so they are gonna be a little more money. I used a pa880(500rms) on a 10'' apline type r and it sounded better than most 500 rms amps.

kookymunsta309 Please answer on my pm & clean ur box