Supercharger pulley change ?

My vortech v2 came stock with a 3.33" inch pulley, I made 9-10 psi with it with a Powepipe. I moved down to a 2.95" pulley and now see 12 psi at 5500 rpm, roughly 14 psi at 6200. You need to measure your pulley first you may be larger than 3.33" like maybe a 3.5???