sub suggestion?? JL250/1, F250 Crew Cab

I will be purchasing a sub woofer for my F-250 crew cab and would like some advice. Whats a good sub to go with my JL250/1? Where to mount sub? Under seat? Behind seat? Sealed or ported box? Replies appreciated.

how much money are you looking at spending ... do you want some sound quality or just quantity ?

I'm just looking for sound quality. I plan on listening to all types of music, not just major thump type music. Quality over quantity.. $ 200. to $500. I would prefer to keep this cost down and still get quality. Reason being the head unit that I'm looking for is around a grand. (AVIC F900BT)

if you are looking for mostly sound quality, one 12" sub in a sealed box should be more than enough. The box will typically be around 1.25-1.5 ft^3 and should fit neatly under the rear seat.

Thats what I was thinking... One good sub versus two. Today I went to a sound shop to start getting my quotes. His idea was two 10" JL woofers in a ported box behind the seat. Its part of a package deal that JL has with a JL250 and two JL 10's
( as you know, I allready have the JL250/1) I will end up using advice from this sight, reviews and the shop guy to get my dollars to work. I'm in the dark. With hope it will turn out good. BTW I have chosen to buy the head unit from a shop ( versus online to retain the warranty and service commitment) more money but more security.