IO - Not a bad likeness, though mine generally looks angrier than that. Must be a brother.
BPF makes a fair point for the warrior, but my interpretation of the original question was that lagentium was looking for a generic answer. I think we've got as far as 'you can expect some degradation but if you have an engine management system then you stand the best chance of achieving or getting close to the book values without mucking up your engine'