So I bought my 06 and it came with 2-way 6.5s by rockford fosgate. Installed an alpine HU w/ modifry and going to install the alpine mini-amp this weekend. Since my car has two tweeters behind each seat and what appears to be an independent tweeter in each door, do I really need the additional tweeter attached to the 2-ways? Could I go with a 6.5 crossed and have better sound? Whats wrong with this thinking?

 

I think you'll be fine with just a woofer in the door and a matching tweeter in the stock tweeter location. I'm not sure on the specifics of your particular set of speakers as far as wiring goes. They may not have been designed as a 2-way component set. But any component set that you buy that is advertised as 2-way will just have a woofer and a separate tweeter that would go in the factory locations.