I’m thinking of getting an EMS in the car to monitor the following: Turbo Boost, Exhaust Temperature, Oil Temperature, Oil Pressure, and Air to Fuel Ratio. What’s the most popular and easiest to program? Motec, DFI, Haltech, Apex, Greddy, HKS or Apex system . . . Should I use their own display or get a Stack display? Thanks . . .

 

buying an EMS can monitor these things but you will have to have a datalogger in the car with you to read it. the easiest thing to do is just get Gauges. you can get cheap ones from Autometer or even places like advanced auto and autozone. that's the cheaperst and and easiest way to read ur car's vitals. here's what i would suggest:
boost
egt
o2 a/f gauge (wideband will do sooooo much more and you can tune with it, but a narrowband will keep you from leaning out so it is usefull but not very)