Hi, has anyone changed a bi xenon projector headlight bulb and was it easy enough to do? thanks.

Yes I did one that failed on my wife's car. There are all sorts of warnings about doing them but I managed to get hold of one off a write off fairly cheap (they are expensive new!) and replaced np - not really any more difficult than changing a normal Halogen bulb tbh. They come complete with the xenon charge 'pack' but are just plug and play.

The warnings exist because some/many clueless motorist with a failed light bulb will "hot plug" a new bulb to see if it works before final commitment to the lens assembly.

How may people similar daft/clueless people change light bulbs in their houses with the power on?

The power/energy is proportional to the square of the voltage (and current). Also high voltage will jump further (because it breaks down insulation much better). So whilst a mains shock will disturb you a high voltage and thus associated high current (unless restrictively limited to a few mA) will cause significant skin burning/damage and can be extremely lethal.

Sadly these high caution yellow triangle signs are treated with the same lack of respect as wet paint signs. "I wonder if it is still wet" as finger is pushed forward!