True, adding a box tube to tie in the front and rear subframes will be stronger and building a cage that ties into the box tube will be even stronger. But for the average Joe that just wants to stiffen a failing stock rail, the Bad Dog rails are more than adaquate. And adding the BD subframe connector to a new rail makes things alot stiffer than stock ever was.I designed and fabricate the BD rails and subframe connectors and they are purposley made for the average joe.They were designed to fit over the stock rails to minimize installation.That said, they are not for everyone, I am doing an RB swap and have gone the box tube route for the added strength.I'm using 1.5" X 3" with a .120" wall for the main rail. Its mounted half in and half out of the floor pan. It is tied into the rear of the rockers and when I build the 4 point cage, the main hoop will weld directly onto the new frame. This will be plenty strong to handle the added HP.It comes down to needs and abilities...if you dont have the need or the ability to install a full frame, then the BD parts are for you.