There are some ground effects kits out there for lx's, there is one that looks just like a GT, its probably easyer and may even weigh less. You would have to use the original side skirts.
But in my opinion the GT rear bumper is realy ugly, I dont know i think its because of the curve at the bottom of it and you cant see an exhaust tip, I think the tips curve down and that just remindes me of a 80's F-body. And cheese grader tail lights are just sooo sooo sooo cheesy lol, There are better looking body kits or ground effects kits out there, just search around.