A Zetec would have to be putting down 150-155 wheel hp which the same as a stock SVT, and that normally takes intake, complete exhaust, cams (stage 2's maybe), ported head, and a good tune.
Now a 2.3L would probably only need an intake and full exhaust and maybe a tune to be right there with an SVT.
That is what I would guess from what I've seen mod wise and power level wise. Hope this helps..... :-)
2002 Focus Sedan SE
AEM Cai, FC Cam Sprokets, 4 into 1 race header and flex, FS Sport Exhaust, Comp Stage 3 cams and to go in soon a SCT chip.