I don't know about the Vortech kit but the P1SC on the Mustang I'm driving right now makes some pretty good power. On a '98 GT with stock heads, full bolt-ons, Comp274 cams, and a 10psi P1SC it made 400rwhp/385rwtq. So far so good. It makes power up to almost 6000rpm too.
Hopefully it doesn't...