Would anyone know what would happen if i hooked up a 96 GSR ECU to a 00 Civic Si?

both ECU's are OBD2 and both are stock

can someone tell me the exacts of what will happen and if it is not to be done because of damage that it causes to the motor, stuff like that. in detail plz.

 

96 ecu will not fit the 00 model because the ecu plugs changed.

 

Here is a table of ECU swaps for this car. The Hondata site also has ecu swaps for other Hondas