i wouldnt mind driving, if it was worth it price wise... Im looking to get a custom sub box built and put in... or even a MTX or JL.. i havent decided, reviews on either would be greatly appreciated!! I would like to have at least a 12, or two 10's, or even 2 12's would be pretty badass too... and im looking for 2 speakers in the front, 2 in the back, tweeters, powerful amp to kick that systems ***.
i already have an AVIC-N1 headunit so thats no problem...
have you considered doing it yourself? i'm sure you've seen enough episodes of unique whips to know how to build a box. have you looked to see if you can buy already made boxes to fit behind the back seat of your '04 250? other than that, sounds like all you have to do is replace the stock speakers and mount an amp under the seat.
i second that once you get into it audio stuff really isn't that hard with a little research you can get as crazy as you want.
also i have heard the the mtx enclosures for superduty truck are supposed to sound great and you can get them with an amp already on it - basically all you would have to do would be run some power and speaker wire and presto.