AFR = Air/Fuel ratio. On a turbo car I would make sure no part of the curve approaches 13:1 - needs to be 12:1 at tq peak and tailing off to 11:1 or less at redline. Richer = safer to some degree. Lean = disaster.

EGT = exhaust gas temperature. 1600F is the point of failure for burning valves or pistons which have no thermal protection such as coatings or ceramics. Even then, most people don't want to approach 1600F for any sustained time.

Any speed shop should be able to set you up with a good EGT from Autometer for about $100. Figure about another $100-200 to weld in a bung and route the wiring into the cabin to a gauge.