I am also not sure if a retrofit kit will fit in the lightning housing. It looks to be very tight but close to perfect. Bi-xenon Morimoto Mini Stage III Kit (H1)** would be the kit that would maybe fit. Any suggestions?
http://www.theretrofitsource.com/product_info.php?products_id=227
http://www.theretrofitsource.com/product_info.php?products_id=227