All KE systems have a WOT switch and, with one exception that I'm aware of run "open loop;" (ignore the O2 sensor) and enrich the mixture to near the ideal for maximum power 12.5:1 A/F ratio at WOT.

The only exception I am aware are certain V-12 600SELs from the early nineties era. The second year out the power rating was reduced from something like 402 to 389. The sole reason for the change was elimination of WOT enrichment, so those models run closed loop all the time when warmed up.

Most cars have WOT enrichment, and it has no effect on emissions because they never touch WOT during the certification test, however, EPA is phasing in a more aggressive test with higher acceleration rates, speeds, and use of the A/C. Some low powered cars will probably require WOT, and some may have to eliminate WOT enrichment to pass the emissions bogeys.

No WOT enrichment can cause catalyst overheating if WOT is held for a sustained period. If there is WOT enrichment, essentially all the O2 is consumed in combustion and there is not enough in the engine out exhaust to support reaction in the catalyst, so the catalyst will not overheat.

Duke