On an S13? Look at the back of the hub face, its not flat but webbed, you wont be able to redrill it without going through a web.
Fair enough knew there must be a reason why it isn't done. Cheers will continue searchin for 5 stud hubs
There is no problem to drill front S13 4 to 5 studs, have seen that and its working well. For rears its no way!