also by putting a 16v or zetec head your not gaining much, maybe just better air flow. the better option would be to keep the cvh head, but use a 2.0 zetec bottom end, this way you would have a 2.0 but with all the benifits of a cvh head, its also a cheaper way as you can keep all the original manifolds ect.

or you could go for full zetec turbo

what mods you done for 20psi?