1/ I changed the sparkplugs, the old plugs (90k miles) still look good and the gap are 0.035mm for 5 of them and one of them has 0.04mm. why is it? the book suggest 0.04 mm and why manufacturer put in 0.035 mm? (I own the car since 50k miles)

2/ The new xeon light bulbs bought on ebay item 270176436108
Phillips D2R 4300k Made in Germany (original specs) doesn't bright as the original. everyone else see it more bright?

 

1/ Stay with factory spec 0.04 mm.
0.04mm and 0.035mm could be when they put it on the car, they never check them.
some of the spark plug have different gap, even the brand new one out off the box.
2/ They should looks identical. (It's only in your head, men)

 

New bulbs take about 100 hours of use to get fully "burned in", similar to bedding brake pads.
It takes a while, then the color and brightness should stabilize
Just use them in the daytime to add some hours

There is a reason for cheap bulbs and expensive good bulbs

 

that make sense. thks