don't do it!!! Although the 4Runner and Tundra share the same engine, they have different MAP curves. You need to find the right year charger cuz the piggy back ecu's differ from the 03 and 04. Or, you can completly not use the trd ecu and get some type of fuel management like unichip or splitsecond. Use the search button in the performance section, you'll come across more threads