if you want to bring out the highs definately put some infinity kappa speakers in there, and a custom box wouldnt be too hard for that truck, whats your budget? i can help you piece together a pretty insane system, just shoot me an email and i can help you with any questions you may have, email@example.com
1995 f150 supercab, 5.0 v8, single flowmaster super 40, K&N 57 series intake, 2 12" kicker cvr's and 800
watt rms MA Audio monoblock
In my single cab I took out the seats and replaced them with Corbeau racing seats. I am currently building a center console that will house 2 12" MB Quart Subs and I have MB Quart QSD seperates in the doors.
As far as your extended cab you could but a JL Audio Stealth Box under the back seat and you should be pretty happy and you wouldn't have to lose you back seat. If you really dont care about the backseat then I would go with a custom enclosure with either JL Audio or MB Quart Subs..
I'm actually looking to upgrade my speakers also and possibly add a few subs. I can't wait to tear this beast apart and start replacing the speakers. I've just gotta find the right speakers that I want from Crutchfield and then I'll start.
2007 Ford F150 Supercrew sold
2010 fully loaded Ford Fusion
2002 Mustang GT being built in garage.....stay tuned!!!!
onlinecarstereo.com has great prices. you can buy some stuff at below dealer cost, and they carry a lot more stuff than crutchfield. JL audio makes a great set of mids and highs if you want a better sound you could spend a little more money and go with MB Quart, Kicker also makes good sounding mids and highs
You can get a custom box to fit under the seat in the back and not loose anything. I just got my truck and I can get the 2 10s I had in under the back seat for 200 bucks. All you have to do is move your jack. You can get a box for 2 12's too but you got to make sure you have enough airspace for them. It just all depends if you want to shake the car next to you or not. I mean 2 good 10's will get it thumping real good.