I highly recommend this unit
Automobile Multimeter for EGT, Boost, Red [SYL-1813R] - $48.50 : auberins.com, Temperature control solutions for home and industry
Their page is weak to say the least and you do have to buy the probe separately.
What I like (and it is not clear on their page, make sure you email them) is that it has outputs you can program to do whatever you like under certain conditions.
Mine is easy -- I hooked up a 5 buck seat belt alarm when EGT exceeds 1270 degress and it goes back off when I drop under 1250.
The purpose of an EGT gauge is to watch the EFT temps. Even experienced drivers can miss something. Experience tells you when you should be having a problem. But that does not always work and the loud alarm saves your engine.
I had a problem once ... running fine and I was on the freeway. Suddenly my alram screamed and since I was on the flat at 55 I was surprised. Turned out an air hose came off and I was losing all the boost ... and when I put my foot down black as heck smoke. But, the alarm found it first.
You can also drive solonoids and in theory mess with fuel and boost and all kinds of things.
It also has memory which I like, and it has a way to wire the headlight switch in to dim it at night which works perfectly. I simply tapped a dash light.
I velcroed it to the bottom of my A/C disperser (Vintage A/C) on the left -- this was a plus, no holes in my dash, etc.
For some the digital look may be offensive ... but it is actually so small I don't find it so.
I also used the "Tiny Tach" -- a small digital tach that is also very nice.
Eric