As above on two counts.

Are the silver top and black top cam pulleys interchangable?

and..

Are silver top and black top crank puleys interchangable?

On the same note:
Would you buy either of these for a silver top?

FORD FOCUS 1.8 2.0 ZETEC ENGINE CRANK PULLEY 2000-2005 on eBay (end time 29-Nov-10 17:12:21 GMT)

Zetec Vernier pulleys on eBay (end time 14-Nov-10 16:54:37 GMT)

or

Adjustable Cam Pulleys

I can't answer your question but the OBX pulleys fit on the exhaust cam of the ST170 engine.

Dusty,

Does that mean you didn't try the inlet?

I've got a Piper pulley on the exhaust cam of mine.

Only way to get one on the ST170 inlet is to ditch the VVT system.

[Edited on 5/11/10 by coozer]

wouldn't bother with the crank pulley. I very much doubt you will see any power increase, and bear in mind it is probably made from recycled coke cans in a shed in china, I wouldn't trust the quality at all. Plus the OE ones have a damper in them, something glaringly missing from these. Of course, the damper isn't really needed, which is why Ford spent out and put one there in the first place (and Ford doesn't like speding money unneccessarily)
Stuff like this should not be bought on price or claims pulled from nowhere, but on proven quality.