On a single turbo FD, What gauge is important other than Boost gauge, water temp gauge, A/F gauge?

 

I'd go with as many different guages to regulate oil as possible (pressure, temp...) if I already had the ones you listed cause God knows you need to keep an eye on that stuff.

 

EGT is a good one to have as well. Some would say it is more important than A/F (if you know what your looking for). Sanfordman makes a good point though, oil temp is a very good decision too, I guess it depends on how you drive your car. If you are just a daily driver with the occasional stop light race, what you got is probably enough, but if you track your car for extended periods or just want to know how your car is at all times, then the more the merrier!

Frank