Originally Posted by hogdog

The Focus RS uses exactly the same 'N/A cams' as the 1.8 and 2.0 blacktop engines so yes, you can run a set of 'N/A cams' on the Zetec.

The problem with N/A cams is that they tend to run a longer duration (particularly the inlet cam) than turbo specific cams. That may have been a problem in the past because cams tended to have a very long duration (when compared to the lift). Most modern N/A cams now have a shorter duration (compared to the lift) so it tends not to be a problem.

For example, the duration of the inlet cam on Crower's stage two N/A cams is 256 degrees and the duration of the original Cosworth cams is 265 degrees (IIRC) so even quite an aggressive road cam is still well within the duration limits required for a turbo engine.

As long as the cams don't have a very long duration and the inlet cam isn't massively more aggressive than the exhaust cam then you shouldn't have a problem. Even if you do come across a problem when they're set at 0 degrees it should be easy enough to dial out by retarding the ignition slightly.