I've yet to test the respective accuracies of my two boost gauges, but the EGT accuracy was easy'n cheap to check.
Got a cheapish($30-ish) laser thermometer off ebay.
I use it for other stuff too tho, but it's a handy thing to have in your toolbox.
Pointed at all manner of stuff and annoyed the kids for a few days after receiving it too.
It has settings for specific surfaces too, so it can be more accurate if need be.
But I pointed it at the cast iron area around my EGT sensor at idle and it confirms what my pyrometer indicates.
BTW my pyrometer is a multi gauge 1Gauge too.
Used a brick to hold a few revs to get exhaust a little hotter than the 150 degrees or so at idle too and it still confirms.
Cast iron seems to take a short time to cool down too.
After a bit of a run with EGT approaching 600 degrees I pulled up and quickly did a temp check.
pyrometer settled at about high 200's - low 300's but cast iron area was still in the 500's for a few seconds but quickly dropped, with the bonnet open of course.
After about a min(maybe more, but didn't really watch the time), cast iron area did drop down to low 200's as per the (1Gauge) pyrometer reading.
Also checked the head area temps too.
My coolant temp seems to hover steadily at about 83c almost all of the time, and the alloy housing of the thermostat is basically spot on at that temp according to the IR thermometer. I get some variance along the head, but all in the 80's and some parts in the low 90's near the exhaust ports all at idle of course with bonnet up.
Handy little tackers those cheapie IR thermometers.
I got one that reads up to 1050c .. and confirmed that my kids were fairly healthy whilst in my care for a couple of days(at 35.9c!) :p
my CPU at idle sits at about 27c, my now cold cuppa is at 19c, my health is currently pretty much ok at 34.9c ... etc, etc.
(obviously I need a fresh cuppa tho! :D)

