The front end on the 05-current super duties can be tricky when lifting them. One inch or so and you shouldn't be able to feel a huge difference in handling, go with the spring spacers. 2 inches or more and you start to get bump-steer and "twitchy" handling if you do not correct the angle on the track bar and radius arms. I have a 4" front lift with all the geometry corrected with brackets, and longer springs but have had a lot of problems getting the handling just right. Also I hate how stiff the aftermarket springs are. If I had to do it over again I would probably just go with the 1-1.5" spacer leveling kit, save some money and headaches. You can still run a 35" tire with the sst kit, right?