I need some help installing a system in my 2003 f150 screw. So far i have decided on kdc-x494 hu, mrp-f300 alpine amp, (4) polk db571 in the doors, and a b-8pt sound ordnance powered sub. I mostly listen to hard rock, what improvements could i make w/o spending a fortune?

 

Depends on what your goal is. It looks like you have a decent budget system.
Personally, id scrap the polks in the front doors and get a better set of componets, run the rear speakers off the headunit and the comps off the amp. So a 2 channel amp (or a bridget 4 channel) for the front door speakers or 1, 5/4/3 channel would be best to do with IMO

 

What would you recommend for the front doors? I do not want to do any modifications so i need something that will fit right in. I looked at alpine components because they have a plate to mount tweeter to, but am i gaining anything by mounting the tweeter right next to the woofer in that plate?

 

im not familiar with that year so i dont know what will fit. Most componet sets come with various tweeter mounting options