Hello, If you are going to replace the factory halogen bulbs, I recommend either LED or a higher output halogen bulb. Xenon/HIDs produce too much heat and tend to have problems down the line. Please see the links below for some of my recommendations : https://www.carid.com/2006-jaguar-s-type-led-lights/lumen-led-g10-headlight-conversion-kit-1840172700.html https://www.carid.com/2006-jaguar-s-type-bulbs/piaa-xtreme-white-headlight-replacement-bulbs-1159947837.html https://www.carid.com/2006-jaguar-s-type-bulbs/lumen-vivid-halogen-headlights-bulbs-2621596226.html https://www.carid.com/2006-jaguar-s-type-bulbs/putco-headlight-replacement-bulbs-443606.html