When Is Hot Too Hot?

Also some help to clarify, does a modified street engine run a bit hotter then a 100% stock engine, slantsixdan has already expressed his opinion about this, just curious on other members thoughts on this. Just trying to determine that maybe a car with headers and some engine modification will always be expected to run a bit hotter then stock.

Seabee what degree temperature would you say the gauge I have pictured is at?