I am just starting to replace factory items in my 13 f150 crew cab. I have decided to go only replace the front speaker and add a sub under the back seat. I have the touch screen head unit and don't know if I need to run an amp to the front speakers. I want to install some components that will run me about $150. As far as the sub goes, does anyone have a recommendation for the thinner subs out now? I will be building my own box as budget is important in this build. Any help appreciated.