either of those will essentially be exactly the same, as they don't relocate any of the suspension links.
what you really want to do is triangulate the upper ti-rods to the center of the diff, like right behind the servo mounts on top of the diff, and leave the bottom links set to the outside.
check out
www.rccrawler.com forums for some good ideas on how to stretch your truck, I think they also sell kits to do it.
the problem with just putting longer ti-rods on the uppers and setting them to the outside is your truck will suffer from a LOT of torque roll, whenever you hit the throttle the truck will twist over to the side really far.