Believe what you will but there is no "may" about it. If you were to drive 2 different Jeeps that were setup the same only one with correct steering geometry and one without and take them through situations that required fast hard steering, you would definitely see/feel the difference.
"Must" is a term that is often over used on all forums including this one. That is the reason why I try hard to limit the use of it. What I can tell you is that with 3" of lift or more, I would highly recommend that you do something to help re-center your axle. Is it a "must" to do that? No. So long as you aren't seeing any problems with rubbing at a full turn/flex, you can definitely drive around with your front axle off center. At 3" of lift or more, I would also recommend that you correct your steering geometry as well and if there is a "must" here, it's that BOTH your track bar and drag link need remain parallel to each other - the best way to do this is through the installation of something like the EVO kit. Just because you didn't see a "BIG improvement" doesn't mean that your steering geometry isn't better or that you wouldn't benefit from it when it's really needed. Certainly, I doubt that you saw a BIG difference let alone any after you installed your RCX Diff Guards - why not remove and return them so that you could use that $$ on a different mod? Just trying to put things into perspective.
It's all good, not saying that you did.
