For the metal resistors originally - check out this DIY which uses our de360 fogs:
DIY showing where you can place the resistors
our de360 can be turned 360 degrees so you can find the best spot in your reflector housing which means it offers the best beam angle vs other models where you cannot turn the LED so you are stuck wherever the bulb points in your housing which can lead to a bad beam angle or blinding glare.
listing for the de360 fog LEDs:
http://deautokey.com/product/mk6-gti-complete-led-fog-light-kit
And we have a lifetime warranty if you have any issues we will replace these for you.
But it is very interesting they worked error free - do you have any other vcd mods that could have eliminated the errors on those?
Even the listing you shared suggest load resistors for error free operation.