The Silverstars are much brighter
(than standard) Unfortunately, I needed to fit the +50% Halfwitts variety, and I haven't noticed so good an improvement.
True enough, new bulbs often do affect the beam setting slightly. If there is still a beam pattern (a horizontal line with a kick up to the nearside verge), then it can be assumed the bulbs are fitted correctly.
Jason, I approached some auto bulb suppliers (with little success), and have been told that the 100w bulbs likely outperform the high output replacement bulbs, but only for a short while. I view this with some scepticism, but I agree that the whiter light is easier to see with, and it produces less glare than the 100w bulb. Also, the 100w bulb may not have the necessary UV filters and the plastic lens of newer cars would soon become yellow.
The greater heat produced dictates that the 100w bulb should have a shorter service life.
Despite my enquiries, I still have no reason as to why the H7 bulb is so popular. In my experience it offers a much shorter bulb life than an H1, and I have found no obvious advantages. Change for the sake of change, I suppose.