i was just scrolling through a few online catalogs and sites. and now i'm curious about something. i've noticed on VT's website they have a bunch of both PI and nPI cams tochoose from. what would be the biggest difference between doing a cam swap with aftermarket nPI cams and doing a cam swap with aftermarket PI cams? do PI cams not go into nPI heads? i just re-read the sticky, and i'm trying to piece things together. what would be the point of going to PI cams when they have aftermarket nPI cams for the same price with the same specs? something i've overlooked. and this would be keeping the nPI heads with say PI intake.