Do i really need sub frame connectors???

id like to do what that guy did with his frame conectors and but them up against the floor, does this serve any advantage, and do you box the top in or does it not mater? about how long of square tubing do you guys get to do this, id like to do this to my cuda but unsure how long i need the metal to be. and in the rear do i wanna expaind the rear conection on the frame conector over the rear leaf spring or can i just but it up against and perhaps put a plate over it :scratch: (did anyone get what im trying to say) i confused myself and what about conecting the frame conector to the rocker will this really help out my car, is it sugested, and i also dont wanna cut my floor its in really good condition plus i dont want a bump in the rear floor from the frame conector