I have been running a 180 degree thermostat with the aluminum radiator and my temp gauge always reads around 170 degrees.
Well the most common issue ids the gauge not reading correct.
Take the sensor out groud the body and heat u with an accurate mercury themoeter in a jug of water connected to the guage...varify the gauge
Automotive temp gauges are not highly accrute and nor designed to be.
As to run 180 or 195?
well lets get into the real world....yes As smokey says more power devaloped at higher temps..BUT that also takes into considreation other stuff like machining tolerances matched to suit...are yours
Now lets take common sense further..
This more power is at a narrow max power rpm band width WoT....or in other words on the track.....Anywhere else ...well taking off from an interesction , hit the other side back off...hit the rpm range, and if did long enough diff between a 180 and 195 wouldnt make a scrap of difference
On a road trip open highway, not even close to rpm range and using maybe 20 hp.
So unless a full out track car looking for that tiny edge over the rest of the feild 180 against the 195 not a scape of difference