ok... I've been reading/searching on here and the rest of the net for a few hours my eyes are now bloodshot, so Im just gonna ask a few!
Does anybody have any links/info to help me understand gearing?  Im putting 225/75/16s on my 2.0L auto vit since I've been told stock gearing can handle 29's.  But of course I want to go bigger, So I need to learn more about gears..
-also-
What can I use to recalibrate the speedo/odo after the bigger meats? 
Thanks guys
James

There's a company in Australia that sells a speedo recalibrator box called Yellow Box.  I have one.  You wire it in between the computer and the dash and your gauges will indicate correctly after you adjust it.  Works great...I'm just too lazy to ever make the time to do mine.  Luckily I salvaged ours after our '03 was wrecked.

thanks man,  I found their page http://www.yellr.com/order.htm
are they the only company that makes them?

That I know of.  They were easy to deal with and the transaction and shipment happened easily and efficiently.