pully kit for 4a-gze

[ae86ln]

im looking at buying a pullyey kit for my supercharger. and i was wondering if anyone has bought off these guys before

http://www.pulleybros.com.au/page8.php

a 3pk belt is pretty thin, does it slip alot. and how much boost would a 103mm pulley make on a ae101 4a-gze motor everything else is stand.

thanks lew