Congrats on 4300 posts exactly
I know CVH turbo engines can produce good bhp gains but they are still only 8v and upto 400cc less - never mind the torwue difference.
There are many many differences between the two engines but the zetec will take more, heres a typical example: FRST conrods good for say 230/250bhp, Zetec conrods good for 450bhp.
Its more model technoligy but alot more advantages over the old CVH, dont get me wrong its great and all but I think zetec turbo wins the battle.
The american tallblock 1.9 engines are of short supply, and even then that doesnt give the full 2000cc's against its predicessor