yes, there are a lot of roumours about ST170 engines.
i used to build ST internals into silvertop blocks and use silvertop heads to loose the VVT setup, they are NOT electronic operated and use centrifugal force with pressure opperated gel to make the cam pulleys advance/retard.
they are electronicaly sensed to advance/retard ECU effects on fuel/spark maps.

they ran forged rods and pistons, longer rods and very shallow pocketed pistons and look very very well engineered for a mass produced motor.

ST170`s do have completley different heads to any other 2.0 zetec (which is basicaly a modded black top 2.0)

if you look on a petruding front facing lug on cylnder head it has SVT stamped into it, this proves an ST170 head.

they have high lift cams, stronger springs, slight change in port shape and one off head cast that accepts VVT setup, normal non ST cams/valvetrain in not compatable in ST heads, journals and pulleys etc simply do not mate up with the head.

each head was specificaly biult by hand and shipped to be mated to botom end and fitted to production car.

any questions at all you may have, please ask

regards Sean