When I did my swap, I only had enough money for an Air/Fuel gauge and a boost gauge. However I wish I saved up and bought an oil temp gauge and a water temp gauge. I don't really trust the stock temperature gauge, and I really wish I had some way of making sure my oil pressure was ok. At a minimum I recommend everyone buy at least 3 of these, with the water temp gauge being the optional one.
I also wish that instead of an air/fuel gauge I saved up money for a wideband lambda meter setup to tell me my exact a/f ratio. There are some reasonably priced kits out there that I plan to get in the future, but it would be very nice to have from the start. However this is just a nice tuning tool that allows you to tune off the dyno. It's by no means something I'd consider necessary
