Under the seat speakers.
 

Ran across these today. I have a similar set (older) to these under my seat, and have been very happy with them. I think it is a good solution for those that do not want to hack the doors or use the plastic kick panels.

http://www.lafayetteradio.com/Speakers/TS-X200.htm

LB, you can't compete with your neighbors with those dinky speakers. You need some like this. :p
http://www.wardsweb.org/audio/extrem...s/satolftc.jpg

Holy F-word. That is H-U-G-E.

HAHAHAHA Putter!!! holy F word Batman :D I am planning on building some boxes for mine to fit under the seat and install some 6x 9's. The doors on mine are alreay hacked with speakers in them, so I'm gonna use them until they crap out and then I will take em out and weld the holes shut

i have a pair of pioneer truck riders that are a few years old, but i couldn't tell you the specs. but for two eight inch speakers with tweeters they can really bump. I also have some pioneers hacked into my doors. I don't know much but ido know that i was impressed with the sound of these speakers vs the size of them

if you put the speakers like fred t has up there in the bed you wount need cab speakers :lol: but the neighers and other people on the road may not like you much :rolleyes:

Kenwood and Infinity make some powered subs that might fit under the seat. Not sure though, I don't have a truck to measure, I've got a Blazer so no worries about a speaker box location, haha. Check this link and scroll down the list to Kenwood and Infinity.
http://www.crutchfield.com/S-PKsDC6m...&avf=N&search=

I think you would also have to tow a generator to have enough power to run them.