AlexSpeed,

That "scratchy" sound results from the ABN Webra, as well as all other ABN/ABC/Plasma ceramic engines' cylinder bores being tapered. The internal diameter of the sleeve is slightly smaller at the top, than at the bottom.

When the engine reaches operating temperature, this taper is "canceled out" by the differential heating of the sleeve.
This, since the top heats and expands much more than the bottom.

This is why such engines must be broken-in at operating temperature, unlike ringed engines that need a very rich and lukewarm initial break-in.

You can search the pages of old RCU for the "break-in in tapered bore engines" thread.

When cold, your Webra must still have a slight "pinch" at TDC. If an ABN/ABC/Plasma ceramic engine is broken in four-cycling, slobbery, dribbly rich, this "pinch" will be gone and the engine will be ready for an overhaul...

Not broken-in - just broken...