I totally agree with Peterc. Upgrades are great for bringing the car up to date, But believe it or not I'm more interested in Resolving the issue at hand before someone installs one of my upgrades. Write-up upon write-up has been done on updating, cleaning, improving and resolving electrical issues in the S30's. The Key points are always this......... Good battery and clean battery posts. Battery Corrosion is typically the cause of resistance and bad power flow (drawing more than the bad connections can handle.) New or Larger battery cables. Clean connections on both ends (Battery post clamps and ring terminals) Fireman don't bring a garden hose to the fire, they bring a FIRE hose. Power transfer is essential in ANY vehicle. If the vehicles body is one larger ground plain, shouldn't the battery have a better connection to the body then the stock, wimpy 6 gauge. I always suggest a 4 gauge upgrade but I personally use 2 gauge power wire. A 60 amp alternator will increase the battery refresh rate when coupled with better power wires connected to a good battery. Most people who do the ZX alternator upgrade, claim better headlights at an idle, brighter lights all around the car, faster wipers, better idle do to better power to the ignition system (points, coil, key, etc) The headlight upgrade harness will add relays to the headlight circuit. Thus reducing general power flow thru the fusebox, combo switch, and all other wiring associated with the headlights. The power to the headlights is now going straight from the battery, to the realys, to the headlights in a much shorter run, and the headlight circuit now only controls the relays. The parking light upgrade harness works on the same principle. It adds a relay after the combo switch, which puts a true 12 volts back into the system, bypassing the fusebox and combo switch as high current units. The result is brighter exterior lights and dash lights, and no more melted fusebox and failing combo switch. GROUND, GROUNDS, GROUNDS!!! Make sure all of your grounds are up to date. Unscrew them, clean them, clean the surface they are connected to and rebolt them, tightly. The HLH comes with new ground wires and the surface should be ground to the bare metal, attach the ground wire to the inner frame using the inner lower valance bolts, then coat with dielectric grease over the exposed metal to prevent rust or moisture from interupting that good ground. Hopefully this will get you started to an all around better electrical system. Dave