The only problem is that SVT and Cosworth already squeezed about as much as they could from the Zetec motor in making the SVT. The only way to make decent power gains is to go forced induction, which it takes to very well.
Mine: 2006 Mazda3 s GT Hatch: 111k, Gray, Manual
Gone: 2002 SVT, #1654
Hers: 2010 Focus SES: 84k, Ebony, Auto, Moon and Tune