I checked with the service department at my Lexus dealer. They said that if/when TRD develops the supercharger for the IS-F and it is dealer installed, the warantee will not be impacted.
The early numbers I had seen on the ZR-1 was in the 550 - 600 hp range, and yes, I understand the power to weight impacts. Still, it would be fun to see the shock on the ZR-1 driver's face if a docile looking street car (the IS-F) stayed even close to him.