Not quite sure why there is any idea of changing engines! The British Apache outperforms a 'D'. What it does need is all the other parts of the 'E' upgrade and there is no reason why this cannot be carried out in the U.K under Boeing . Its pie in the sky to believe they will just go and buy new when its more than possible to carry out the American 'E' Mods and incorporate ASPI at the same time. Its not a hugely complicated airframe .