Firstly, it's probably not a duratec engine, more likely to be a zetec engine with 'duratec' written on the top. You're never going to get masses of power, Induction mods, fullexhaust (and mani) will see 10bhp or so, some decent cams can take that up more so, but still not much for the cost. Best bet would be to find a 2nd hand st150 engine, and stick that in.