Whatever your stock bulb is that is the HID kit you want. Although I would google around and see what the HID cutoff is like with whatever brand of projectors you have. If its not a good, crisp cutoff you will not want HIDs in said projectors.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.