I re-geared mine, but when I went to 35's. I would NOT recommend re-gearing for OEM size tires. Waste of money.
As for the Superchips, good call! Do it.
As for warranty, do a web search on the Magnuson Moss Act of 1979. Any modification voids the warranty on a given PART (NEVER the whole vehicle- most misunderstood thing in all of car-dom!!!) ONLY if it can be PROVEN that the aftermarket (modified) part caused the issue in question.
So, re-gearing WOULD void warranty on most of the axle parts. MAYBE you could get around it with SOME dealerships, but don't count on it!
As for the Superchips, it COULD void the warranty on the ECU, engine, transmission, and any electrical parts between. However, you can remove the programming with little to no electrical "signature" that says it was installed.
Use any mods, as always, at your own risk- Mark W.