So I currently have a 94 Integra RS, but when I purchased it, the car came with an OBD2 LS in it. Now I want to swap a GSR b18c engine into it. Would I have any complications or should I just go with the plug and play/wire vtec.

 

Also the GSR engine is an OBD2 engine. Should I use the OBD1 ecu or OBD2 one?

 

OBD1 ECU for sure and engine if you can get it. If you get an OBD1 engine everything should be plug and play. You'll need to wire up VTEC solenoid, VTEC pressure switch, knock sensor and the IAB's on the intake manifold. PM me if you have any wiring questions.