If I use an '00 Si EWH & ECU in my '98 EX, what other electrical mods are needed for the B16A2 swap (I bought a complete '00 Si that was wrecked)?

 

Dash harness. No point in swapping the engine harness though. Just use an OBD2A to B ECU adapter and use your harness. Everything will plug and play from your EX harness with the exception of maybe the CKF connector which will need to be converted.