The harness may be okay, but the switch is probably the weaker point. I put halogens in my Midget and while they were brighter, it overheated the high beam switch and ended up with no headlights one night. If you do, you might want to consider relays, and running a separate lead to the headlights. I put two relays in, one for the highs and one for the lows. Now my dash lights are brighter, the wipers run faster, and the headlights themselves are brighter. Oh yeah, I also put fuses in the lows and highs too, since they didn't have any fuses originally.