Upgrading sound on 2005 F150 SuperCab without changing head unit or losing cab space.?

plain and simple, you wont get good S.Q out a factory head unit! It is the first thing youll need to build a nice system.

keeping the factory radio is a very good idea for many reasons

one that nobody is going to steal it

I did a system on a 2004 speakers replace with 6x8 3 way pioneers $70.00 i use a dei 5 channel amplifier 50w x 4 + 1x150w and one single 10 woofer jbl under the rear seat

customer was very happy with the sound and the truck look factory because we keep the factory radio we use a hi/low adapter from audiolink and we also use the frd-04 aux interfae to plug the xm and the ipod to the factory radio

good luck with the installation

I realize you like the stock head unit, but remember that the sound quality is only going to be as good as that head unit can allow, it will definately be your weakest link. With that said, look around for some JBL, alpine, or blaupunkt speakers. You don't want anything too crazy for your 6x8's so that your stock head unit can still move them (in otherwords, don't go hunting around for something with giant magnets thinking you're going to get better sound. You want efficiency)

As for the sub, go with a bazooka or the like. They are reasonably priced, sound great, are easy to install AND remove if you need to, and everything is in one nice neet little package. Enjoy.

The answer is YES you can! In addition -as I am a Honda owner myself- I know by experience that Honda is originally placing sensitive speakers. So the head-unit is putting out sufficient power but if you'd like to have equivalent or (usually) better sound than before you'll need speakers of at least 92dB sensitivity. For example my Civic which is of almost the same age as yours -but European model- needed speakers of 92dB front and 93dB rear to sound equally loud but much much better than originals.

MTX offers loaded enclosures for your vehicle. They offer a 200wrms powered version also. Won't even know it's there... till the bass hits...