If I replace my F22B2 with an F23A1, would I have to replace the tranny and ecu also? Anything else?

 

no, the tranny and ecu are the same.

 

not true. F23a1 is OBD2b and the harness and sensors are different. If you used your oem intake manifolld and throttle body then you could use your oem ecu as long as you are doing manual tranny.

OBD2b accord trannies are different than OBD2a ones for automatics so you would have to either convert your car to OBD2b to run an auto tranny or switch to a 5th gen tranny.