I changed to lower thermostat and it didn't do anything for the high side.
Stock system operated from 205 - 230 (factory fan doesn't turn on until 225)
I replaced with the 193 thermostat, it then operated 195 - 230 it's hot here all the time.
I then reprogrammed the fan to come on at 215, so car now operates 195-220.

So unless you live in a cooler area, don't bother, lower thermostat won't do much.