In Reply to: 2-3 hours work for a competent auto electrician posted by Jon Lewis on March 03, 2001 at 12:13:59:
Whelp, thanks again.
1989 E30 M3
assuming the new wiring kits are already put together and all he has to do is tap the power feeds and then plug-n-play. you can reduce that if you remove the orignial buckets yourself - a 20 minute job - and then mount the new buckets. for someone inexperienced with automotive electricals, the project could easily become a day-long affair. i essentially did it twice because i didn't like my first solution. total time was about 8 hours but assembling the new harnesses was another 3+ hours.
euro lamps need at least one (1) relay wired to the high-beam filament of the outside (ellipsoid or low-beam) lamp. that's right, euro lamps increase the wattage to the "low-beam" when the high-beams are engaged. that's where most of the notable increase over the u.s. lamps comes from. if this step is skipped, the improvement is almost non-existent.
if you stick with standard wattages - and your wiring is in fantastic shape - you can safely use the factory wiring for the low-beam opeation - and for the high-beam (you still need at least the single relay above). if so, you must change the wiring looms' plugs from the 9006/5 ends to those for the h4 bulbs. using cheap, clip-on wiring connectors is not recommeded. i strongly suggest soldering quality connectors to the wiring loom and also using heat-shrink tubing because of the moisture concerns. i go a step futher and use a "liqid electrical tape" product from napa before the heat shrink tubing.
if you want to upgrade to high-wattage bulbs for both low & high-beams, it's best to use three (3) relays with one triggered from the stock looms low-beam feed and two (2) triggered from the stock looms high-beam feed. quality relays with slide-together connectors from hella cost about $12 each in 12v 40amp versions.
you WILL lose the check light functionality altogether unless you simultaneously wire the stock loom's ground leads into the relay's ground terminals. it is a time-consuming but not overly complex wiring project.
i've done this project and there is some noticable improvement. it is not extraordinary however. and it's nothing compared to the 6.5" lamps of the hella 500 driving lamps mounted on my front bumper - now those light up the road but i must remove the entire lamp to raise the hood, ugh.