Isn't the fuel ratio and stuff different. To my knowledge the ex is also a sohc w/ vtec. Most of the Gsr's power is also up towards the "stock" redline. All i know is that it is a very small engine. why did you put that ecu into a gsr? I dont think that it would fit with stock harness.
Yeah I though B (DOHC)series engines have a different wiring harness to the computer compared to a D (SOHC) series engine......are you sure it`s even a civic ecu? What is the code on the ECU say? (for example: P28) For an ODB1 GSR you should have a P72 ECU.
you can have the p28 ecu reprogrammed for a GSR. Also, the D and B series plugs are the same. Just that some have more wires than others. Like non vtec cars you have to run the wires for them. I had a 93 Civic DX with a B18B1 engine and the ecu pluged right into it. No mods had to be done what so ever.