hc_416

I think mandatory gauges are oil temp, oil pressure, afr and boost. With out those you have no clue what your engine is doing and wont have time to pull over to save your car. If you look at any boosted OEM car they include some if not more of these gauges. At least and not recommend you could do a ecuteck Bluetooth ODB2 reader. Use it to stream to a phone or tablet, so there is really no reason to have no monitoring at all. Also not trying to come off as a gauge d bag, just my my 2 cents

Boost gauge - You will be able to see boost creep, lose of boost after hitting peak, a boost spike, etc...

Oil temp - The VHR runs hot so you will be able to know when you need to cool down,( say a race track, or spirited driving, drag strip)

Oil Pressure - Will save your engine if you loose pressure or see droping pressure.

AFR - Will let you know if you have a problem with fueling.