Several posters said they were disappointed with the Sylvania premium bulbs. I also tried them on another car and was not impressed, so I stopped buying them. I remembered reading recently there was a lawsuit relating to the misrepresentations to the performance. I did a quick google search and found this:
https://autolightclaims.com/mainpage/Notice.aspx
It says a proposed 30 million settlement has been reached with Osram Sylvania.