What is the best vortech supercharger for 99-04 pi mustang gt?

I have a 1996 Mustang gt. I have been building a motor for my car this past year and so far I have a 4.6L block bored .020, with a crank thats rated at about 600 hp (its not forged) with forged H-beam rods and Forged Probe pistons. I will soon be buying the 99-04 PI head kit. I have decided that the vortech supercharger is going to be the best for me (I wish I could afford a kenne bell but the price just seems out of the question) so my question is what vortech supercharger kit would get me around 450 hp. I see only one on American Muscle that gives around 405hp but that does not seem like a smart choice buying a supercharger from AM. Also with my bottom end what would be a safe psi to run,and i want the SC to really scream. I know I have a lot of questions; when it finally comes to buying a supercharger I really want it to be the right one. links would be awesome.