Re: the right amp and subs
JL is good stuff but in the car audio world today, there is much more available that will perform just as well for a fraction of the cost. Look at Sundown Audio, DC Sound Labs, C2 Audio, Tantric Sounds, et al. I would hop onto the classifieds section of this site, lots of good gear and from what I can tell, most of the sellers here are genuine and honest people. I've bought a few things here and they were exactly as advertised.
Also, regardless of the amps and subs/speakers you use, make sure to get the foundation laid well or nothing you do will be up to par. What I mean by that is, get the electrical system in shape before you start worrying about the other end. Id you're gonna be running close to a thousand watts to begin with (and we all know he'll want more soon), go ahead and invest in a run of 1/0 to the back and do a big three in 1/0. That way, you'll have enough power to keep signals clean and protect the amps and subs you do end up using. 1/0 CCA will carry about 300 amps and can be had on a modest budget. Check with @mylows10 for prices on Sky High Audio amp and big three kits.
As for the other end, I'm a big fan of one woofer setups and when in the right box, one woofer can be stupid loud. Especially in a huge cabin like you have to work with. One good ten in a t-line on 500 watts in that truck will sound like a lot of 15s do in cars.
And lastly, as was mentioned, share some details about the equipment you already have. There's a little more to advising about it than just knowing power ratings.
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