if i have to replace the motor would i also need to replace the regulator?The motor could be the same but I doubt the regulator is.
Look the part up here http://nissan.epc-data.com/silvia/s15/
and then enter the part number on here http://www.online-parts.co.uk/nissa...7695339_1660091f00-injector.html#.VNqSh0aQGc0
that will give you a price!
Then if you want to cross reference it with an S14 look up the part on here http://nissan4u.com/parts/200sx/er_s14/1999_9/