I've done this already, its easy, u should be able to use you stock harness, all you would need to do is use ur OBD1 distibutor and then get the 99-00 SI Injector plugs, cut yours off and splice the si ones on, then add the Vtec wires, if you use a harness from a 92-95 civic ex or si you dont need to add anything jus plug it in and lengthen your vtec wires to reach around the distributor, as for ECU use a chipped P28 or what i like since i have used both, i use a P30 from the Del Sol, that way you can run wires to hook up the knock sensor, then jus get that chipped, when i ran my skunk 2 chipped p28 it ran good but it ran really good with a stock P30 so i stayed with that. oh and also an obd1 b16a3 exhaust manifold or header due to the fact the 99-00 si was obd2 and has two O2 sensors, one in front of the cat and one behind so there should not be any O2 sensor housing in the stock manifold. other than that u should be cool B)