I also had issues with a set of superbrightleds license plate bulbs. I don't feel that it's a quality issue, it's the voltage range that they're built to handle. After they quit working for me I went to the parts store for some stock replacements. After about two months, one of them had burned up and both of them had warped the lens they mount in. So basically, even what the parts store says will work still isn't up to the task. The other link they are posting is meant for higher voltage and have worked great for me since August.
08 Focus SE Ice Blue
Steeda CAI and Strut Brace, 17" Racing Dynamic wheels, Big 3 w/ TB wire, other goodies on the way!