i'm tired of having a nice cd player and terrible speakers!! i want new ones. i have the stock 3.5"s in the dash and 4x10"s in the back and was wondering it i could go any bigger or better with out spending insane amounts of money. (i know guy who is an alpine dealer and he installs stuff for free for friends so this shouldn't be too hard) so would it be possible to put 6x9s in that back where the 4x10s are now? and can i put anything else in the dash? or is 3.5" about it? and i was also thinkin ... 4 speakers is not enough for a truck this big. would it be possible to install some like 6.5"s in the rear doors?