Thats got the excellent Zetec Engine (even though dressed up as the Duratec that replaced it)! Can be N/A tuned easily to 200bhp. Maybe K&N, Decent Exhaust (inc. Exhaust Manifold), Performance Cams and Megasquirt ECU (or ECU Re-Map if they can be Re-Mapped). At a guess this could take it to 200bhp.

Dave