First thing would be to get Toms Turbo/Supergharger Tune. It will cost you more now but will for ever cover any tuning you will ever need from NA, to Nitrous, to Boost. You will never have to pay for a tune again.
Go 3" on the exhaust CAT back.
The Turbo changes so much between the header and the and intake there is not much to to do there. Larger injectors may be needed so if you ever do anything with your fuel rail it will not give you more power but if you ever pull them for some other reason why not change them.
I am not sure if its still true for the SVT but the regular Zetec is only good on stock internals till the 250 HP range... since the SVT has 50 more HP does that mean it can go to 300HP on stock internals? don't know.
Since the turbo manifolds are all basically custom you should be able to also invest in a high flow CAT if your still doing that. that should not change when you go Turbo.
2001 ZX3 2.0L Zetec-
Hatch Nation #42
Going through Rebuild See "The TICK Build Thread" for details (http://www.focusfanatics.com/forum/showthread.php?t=289168&referrerid=62897)