obdi one harrness buddy way to go, as for vtec just swap the harness you should be fine if you got a p72..and no you can't use your obdii harness at all if worst comes to worst my man call up skunk2 and get a obdII to obdI conversion harness and splice the plugs on your disturbed thats the only real differences in the OBDI and II oh and the II comes with two oxygen senors.. that should be it hope that helps.