does anyone have an opinion on which i would be happier in an 04 scab
polk db570's
or
infinity kappa 682.7cf
i listen to mostly classsic rock, thanks in advance

 

They're both good choices, however, the polks are a better choice if only replacing the factory speakers. Go with the Kappas if you will be wiring in an amp as well.

 

I like the infinity....
You may also want to consider something like this....

http://cgi.ebay.com/04-07-Ford-F150-...QQcmdZViewItem

 

I have had Polk db570's and they were great speakers...They were in my '99 F150. They have a High sensitivity that makes them work well with the under powered factory head units. Polks are very nice and the build quality is the best I have seen in speakers in that price range.....Next in line to the polks I would have to say the Infinity's but they will not sound as good as the polks will sound with your stock stereo. Good luck!

 

I have the Kappa's in the front doors and the Polks in the rear door. Sounds 200% better. I suggest you use dynamat with the new speakers. They will have a lower end and cause the doors to vibrate. The dynamat will kill the panel resonances.
The Kappas are a little brighter then the polks. The two together keep the highs under control.