I have 31" MTR and want to regear. I saw that chart and I figure I'll go wtih 4.11 or 4.27 to gain more power. How is this done and what is the cost to do it myself?
More than likely your 2.5 should have came with 4.11's from the factory. I went with 4.56 gears and I'm very happy with them. You can usually get front and rear gear kits and install kits for @500.00. If you've never done it yourself I would also recommend a professional install them for you.
You ain't gonna see much difference from 4.11 to 4.56. Also, I wouldn't regear unless you plan on upgrading to 33" or larger tires. But if you do, go to 4.88 and be done with it, that way, when/if you go to 33's (or 35's) you'll already be set.