I talked last Fall with some folks from Xerion Avionics in Canadaigua, NY. They have a very nice 5" unit that will show EGT, CHT, RPM, MAP, Fuel Flow, AMPS, Bus Voltage, OAT, , TIT, Oil Temp and Pressure. in a very readable multi-colored display. I was more impressed with what they had than with just about any "new gadget" that I have seen.
As I recall they had delivered single engine units and were working on STC's for ME units including for the Skymaster. Projected cost was stated to be $5K.
I have no concrete info that tells me that they can ultimately deliver, but I'm putting off any panel work to go with my otherwise brand new interior until I'm sure that they can or can't.
(No. I'm not selling for them-I'm simply impressed with something this comprehensive that will fit my panel!)
www.xerionavionix.com
Bob