96GTMust

Im new to the mustang, and car world. I own a 1996 mustang GT Stock. Im planning on putting some bolt on mods, improving the upper intake. I noticed a coolant leak coming from my car and I did my homework and learned about the common intake manifold crossover cracking and leaking in 2000 mustangs and older. So naturally I'm investing in replacing and upgrading my intake manifold. Ive learned that i can install the ford racing pi intake manifold that comes stock on 2001 to 2004 4.6L SOHC 2V V8 GT Mustangs. But from my understanding is i must do a PI swap first because mine is a 1996. So my first question is, is this true? my second question are PI heads Cylinder heads? My third question, will putting this intake manifold upgrade allow me to upgrade my throttle body and plenum to a 75mm? and my fourth question, Is it over all worth it??? I could really use some help and advice.