MuddyOne
See below my totally unscientific method without purchasing devices to fit to your portafilter !!
What i will say after doing this just now, you must be fairly high if you are noticing steam.
See half way through where i get to around 102 degrees. Very little evidence of steam and pressure only around one bar or less.
Starting point with tape was to create flow restriction.
End of video shows checking calibration at 100 degrees in open boiling water.
Befor anyone says this shows the Evo to be reading low, please bear in mind im shifting more volume and flow than on a normal shot. May try later on a genuine shot just to see what im actually brewing at.
@MuddyOne where are you located, your welcome to borrow this meter if it could be any use what so ever.