Yes, I have a focus ZX3 as well, and the Borla exhaust I got for it just made good power on the bottom end and silly crazy pulling power on the mid/upper range, and the intake that I put on it just helpe add to the mid/upper range, and I didnt notice any slack on my lower end, so I am guessing the exhaust would do the same on your tour zetec.
If I were you, I would more than likely get the Brullen exhaust that is goin on. And for the quasi-dual setup you are talking about, it would be totally for looks, and nothing for performance, however if you do, I would ask to get it just like the SVT routes it and get the extra hanger and put it on the passenger side at the same location as the SVTs...
