This truck really doesn't need steel upper links. That will just add more unsprung weight. Are you hucking it off cliffs, or what? A little suspension flex is good, it protects the bulkheads from breaking. Trust me, you will not get this particular truck to handle like it's on rails no matter what you do, even the real ones don't handle that well. Embrace its nature of feeling like it's on the edge of losing control and learn to drive it that way.