I have always preferred the Split Second ARM-1 -- Its very easy to read at a glance, which is important because you dont have much time to look at gauges when you really need to be looking.
The gauges like autometer fluctuate too much..
Here's a link to where I bought mine:
http://www.dynamicracing.com/customer/product.php?productid=81&cat=16&page=1
also, here's what it looks like:
What you need to do to install it is just tap off the O2 sensor, your primary one preferrably.