How are these holding up? Any premature bulb failures or anything?
Sylvania Silverstar Ultras tend to have a reduced life because they have a thinner filament. Sylvania warranties them for 1 year and they quite often burn out not long after that time frame. I still have a set that I've used, along with one from Luminics. Neither will I use again. My night vision is much better now, the big improvement was a combination of the upgraded harness, and Philips Xtreme bulbs.
I didn't attribute my inadequate night vision at the time in part to the ultra white bulbs I was using until after researching how to improve my halogens.