For that kind of money, you should really be looking along the lines of HLCD type speakers. Lightning cans are nothing special, and if anything are more toward the bottom of the barrel.
I REALLY suggest you check out Acme Tops and Tunes in Sacramento (916) 429-2293 (no, I don't work for them!) and I'm almost 100% positive that they will be able to get you into a set of REV10's, an amp to run them, as well as a 12" subwoofer and amp plus EQ for less than the quoted $3,500.00 price. Plus they'll build it right the first time, and you won't have to upgrade unless you eventually want another pair of REV 10's.
IMHO one REV 10, or Exile XM9 will destroy the arc audios or the fosgate 8"'s.
Plus at ACME you can listen to the speakers in an open air environment before you buy them.
Oh, and if you do end up getting REV10's, make sure you buy the neoprene covers for them, it gets rid of the hassle of cleaning bugs off of them after trailering. They are worth their weight in gold!!!