HIDs make a ton difference in lighting, wether you're replacing 20 year old halogen bulbs or not. It utilizes less wattage as well, so it is much more efficient. And I believe you're looking into delving into projector retrofitting, which is completely replacing the stock projectors with another model or aftermarket projectors. We specialize in headlight restoration and custom headlights, and the projectors SC's or Lexus use are the best around and are highly sought after in the projector retrofitting industry, so replacing those with a different projector would be highly based on your preference and not performance. We also exclusively sell the only aftermarket headlight option for the SC's, and those are out of stock until next month and would be the last batch ever made as the manufacturer have decided to stop production on those, and those are only compatible with halogen bulbs and cannot handle HIDs.
Like I said, swapping to HIDs is already a big difference form halogen bulbs. But we can still increase the performance of those projectors with our Projector Lens Upgrade with Tuning service by replacing the glass part of the projector with a more optically clear glass. Please visit our website to see other options or other services we offer for more information.