truck box help

[2010gmc]

So i need some advice on deciding a new setup for my 2010 gmc sierra crew cab. As of now, i have a bad setup with 2 rf p1 12's under the backseat sealed. I wanted to do a ported box like this: http://www.youtube.com/watch?v=rMqdmKnwjL0

however, i talked to a local audio store owner and he said i could never get a good sounding ported box under my seats, any thoughts? He said i should just do 2 JL 10 inch w1's sealed because thats the best setup he's heard in a truck like mine.