It's definitely an upgraded component, cast from stronger stuff. Like the difference between the S3 head and the GTi one.
As jonny says, it's possible its from a higher spec volvo, the S60R maybe. Although, if it's just being cast from stronger stuff, there'd be no need to retool a new mould, so the cost implications wouldn't be too high for a short run of stronger blocks. Or it might be stronger liners.
The old RS Focus had bespoke components and was built in much smaller volumes - there's no reason why the RS wouldn't have bespoke beefed up components? I had some info about the new engine somewhere, I will try and find the link when I get home.
Should be a fun car though, I'm looking forward to trying one out.
EDIT:
Data from a man on the inside. Ford has updated their parts catalogue... (the numbers don't correspond to the actual turbos, that's just the designation of the engine)
Part no.s for engine blocks:
220ps turbo finis 1388501
300ps turbo finis 1757123
One source says he's sure it's different material as on the S60R, the other thinks it's fundamentally the same block but with uprated liners.
Based on part numbers, these appear to be the other major differences, some obviously go without saying!
Inlet Camshaft
Con-rods and pistons
Main and big end bearings
Head gasket
Injectors
Turbo - still some debate over this as apparently some data suggests it the same one
Inter-cooler
Exhaust system
Fuel pump
Radiator
There is a lot that they do share though. Inlet is the same, exhaust cams, crank shaft, oil pump, water pump to name a few.
