Madman? Something else?

I highly reccomend the Madman EMS 3....

while it looks pricey up front, by the time you buy

tacho
temp gauge and sender
egt
boost gauge
oil pressure gauge and sender (or a pilot line unit, same cost)
temp sender for a gearbox
temp sender for the oil
volt gauge
low coolant sensor and system

its usually within cooee of (and often over if you're using the higher quality gauges) the price of the Madman, but what you dont get is the alarm functions, the ability to operate thermofans (or other devices like warning buzzers) or any number of the half a dozen more advanced features the mad man has.

My favorite feature is being able to use it as either a at aglance gauge (multiple bar readings on one guage) or a set and forget system which just sits there showing one instrument until something is out of range, at which point it alarms and switches to the relevent gauge facia.

it also tracks service time and can have a data logger attached to it.