I initially just changed the headunit, which just made the factory speakers sound even worse. what i ended up doing was...
Kenwood KDX-995 Head unit
Kenwood X600F 4 ch amp
Zapco ST1 Mono Amp
Fronts: Rainbow SLC 230.25 5.25 components (tweeters & crossovers)
Rears: Kenwood 5.25's
Sub: 10" kicker
Both the amps fit perfectly behind the drivers side jump seat, jumpseat closes tight like it should, as long as your okay removing the jumpseat back rest. You can see the zapco furthest outboard secured right into the trim indent, while the X600 gets secured with spacer brackets placing it inboard of the Zapco. It spans to the cab floor.
Ive had the system in the truck for about 4 months now and love it. Im glad i got it done when i purchased the truck rather than trying to 'live with the stock system'. The system sounds very full, clear and balanced, esp for the money. I cant speak highly enough for the Rainbow component speakers, or the 995 head unit.
it just dawned on me that your 2011 does not have jumpseats :(