No, its not (nice). How Ford managed to get so little power out of that cc, and deliver that power so badly, is a work of art. On the upside, it won't go fast enough to show up how badly the chassis handles.
Depends what cams are in it. The 1.8s ranged from quite good to "useful only as an offensive weapon". Fit the cams from the 2.0 and they are OK. Good for 130 BHP on standard induction and around 150 on something more interesting. 
I was referring, of course, to the standard Focus engines fitted to lower end models, like the 1.6 I had, and the 1.8 that Mrs TB's brother had, on a works lease scheme when they were Ford employees.
Both were absolutely demolished in a straight line by a K series powered 1.6 Rover 25 (we tried

), which is a larger car. Even more demolished when shown a corner.
I have heard the Zetec is quite tunable (as is the K Series, come to that), but to me, in the Focus, just felt it lacked torque, esp low down. I guess in a 500kg kit car, thats not so much of a problem, and trying to raise the rev limit is more productive? Aren't you getting around 200bhp from your 2l?