http://zilvia.net/f/tech-talk/80712-e5-differences-62-ecu.html
enthalpy;
the ecu’s are interchangeable int he fact that either will run your motor. however. the O2 sensors are not interchangeable and will cause poor gas milage. you should run the O2 sensor that matches your ECU.
skinny for 62/63
fat for E5.
Custom S13 SR/KA ECU Tuning: