The Piaa H3 (high beam) and H7 (low beam) require no changes to the stock system. Have had them in my '02 since the day I brought the bike home. Over 67,000 miles, no problems. Still using the original H7, but replaced the original H3 in May of this year.
The PIAA literature claims higher output with the same power draw. They shouldn't affect the stock wiring. However, BMW uses the minimal ga. wire for the headlight system, with a shared ground. Best solution is the use relays to activate the headlights, or at the least, install a heavier ground lead for both lamps.
Many on this list, and the original, have found the Phillips, Osram or Silverstar bulbs to be equal, if not better than the PIAA's for less $$$.
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