never heard l7's. Have current set up as 2 12" x's on 1200 watts. They get fairly loud and sound great. Two pdx 1.1000's on them would probably be fairly loud and still sound good. id say go for x's if you want sq.
id say go l7 proper amp and itll pound what car is it going in or is an suv if its a car go l7 itll be lound either way shit will rattle but in an suv id go X