Well first you need to know what year this B18 is. If its OBD0 then you can use your current harness and would just have to convert to mpfi. If its a OBD1 motor then you would have to change some plugs, such as the distributor plugs. MPFI= multi port fuel injection. Your car comes from the factory with 2 injectors, which is DPFI, dual port. When you convert to MPFI you manually wire in two(2) more injectors. If your on a budget you can do all this wiring yourself. If your not on a budget then you can get a harness from Rywire. I brought one from them, its great. It will run you about 500$ for everything you need. I recommend you convert to OBD1 while your doing all this. If you go the Rywire route, it will include the OBD0-1 ecu jumper, and OBD1 engine harness. Good Luck