blacklable245

I bought a S13 with the SR swap taken care of, everything has been fine for the past couple of months and no major issues have come up....until now......the 3rd cylinder wont fire, due to the injector harness not getting a signal (only on the 3rd cylinder)....so i decided to go ahead and fix the harness and put the ECU in the right place, passenger side where it should be (right now its at my feet screwed in the plastic under the steering column). I have another harness which i stripped completly of the tape and plastic. My question is, can anyone head me in the right direction on extending this harness and give me any pointers on what to do. I want to do this right the first time so i dont have to keep going back to it. Thanks