I went from 35's (baldish so more like 33's) w/ 4.56's to 5.38's and the difference is phenomenal. I haven't had it up to freeway speeds, but just around town it's awesome. Truely worth it. W/ 33's it might be a little overgeared, and you might be turning higher than stock rpms at freeway speeds--but with the truck lifted and pushing more air, any little bit extra helps. so it depends on what your needs are. It will definitely be a marked improvement in low range. If you plan to go up any bigger in the tire size dept, I'd say go for it.

and w/ your hot 3.4 you'll be able to light 'em up that much easier w/ the lower gears <img src="/forums/images/graemlins/lol.gif" alt="" />