I'll think you'll find the figure's a little higher, an N12 subaru, thats a group 'n' car will make 560 nm on a 32mm restrictor.....
Part of the new rule changes for 2008 mean teams are only allowed a maximum of 5 engines per car and they have to then use one engine for 3 'linked' rallies (to increase reliability) if they defy this rule the FIA impose a penalty, they have just done Citreon on rally mexico, for breaking this rule, although the FIA recinded the penalty when Citreon put the old engine back in the car....
Average engine i'd guess now they'd be looking at 3000km as on average your looking 1000km per rally incl the shakedown (not all competetive)....