Word around the campfire is that the stock 3RZFE bottom end is good for up to about 700HP

The factory 3RZ-FE ECU also has built in capability for running a supercharger

There is a genuine TRD supercharger kit available for the 3RZFE for $10K

When you source your engine, get it out of a hilux with the chassis number starting with a "J" (Japanese Built) not an "M" (malaysian built).