So I take it this car has halogen projectors in it? You can fit HID (Xenon) bulbs in there using an aftermarket kit (such as this http://www.ebay.co.uk/itm/Xenon-HID-...item3a992b4375) which should be a simple plug and play affair with no mods needed to any wiring. Can't say I'm too familiar with the Fiesta's headlight set up - does it have two bulbs, one for dipped and one for main, or one bulb that does both?. If it's two bulbs, you'd need a kit for each bulb you want to upgrade. Be advised though that aftermarket HID ballasts are NOT the same as factory fit ones. There's a reason they cost £15 and not £500. The warm up time is the most noticeable thing, so my personal opinion is they aren't best suited to main beams. Because of the slow warm up time it's very hard to "flash" with them (like to the point that when people with aftermarket HID main beams flash, you can barely tell they're doing it in daylight unless you are looking DIRECTLY at the bulb) and 2) at night you're flicking them on an off a lot, meaning they don't get time to warm up to full brightness before you flick them off.

My advice is to change the projectors in the headlight to the bi xenon Morimoto xenon projector kit from TRS - http://www.ebay.co.uk/itm/Xenon-HID-...item3a992b4375 This will give you both dipped and low beam xenon lighting from a single projector, and assuming the Fiesta has a separate halogen bulb for main beam, you can keep the halogen bulbs in the factory place for additional lighting and flashing.