Sylvania Silverstar)
the other bulbs I mentioned give 100 more hours service on average. I
am looking to replace my stock bulbs which is why I am interested in
this thread, I have not made a descision yet.

"Here's manufacturer data, from internal engineering databases, for
output
and lifespan at 13.2v for H1 bulbs. The numbers here are a composite
of
values applicable to the products of the big three makers (Osram-
Sylvania,
Philips-Narva, Tungsram-GE). Each manufacturer's product in each
category
is slightly different but not significantly so. I picked H1-type bulbs
for this comparison, and while the absolute numbers differ with
different
bulb types, the relative comparison patterns hold good for whatever
bulb
type you consider. Lifespan is given as Tc, the hour figure at which
63.2
percent of the bulbs have failed.

H1 (regular normal):
1550 lumens, 650 hours

Long Life (or "HalogenPlus+")
1460 lumens, 1200 hours

Plus-30 High Efficacy (Osram Super, Sylvania Xtravision, Narva
Rangepower,
Candlepower Bright Light, Tungsram High Output, Philips Premium):
1700 lumens, 350 hours

Plus-50 Ultra High Efficacy (Philips VisionPlus, Osram Silverstar,
Narva
Rangepower+50, Tungsram Megalicht, but not Sylvania Silverstar):
1750 lumens, 350 hours

Blue coated 'extra white' (Osram CoolBlue, Narva Rangepower Blue,
Philips
BlueVision, Tungsram Super Blue or EuroBlue, Sylvania Silverstar):
1380 lumens, 250 hours"