I left the fleet in 2005 when testing was on going, it was looking promising, if you were will to put a lot of noise in the water and loose the element of surprise .
I am going to guess that that you will hit the classified wall very quickly with this conversation and probably not get a reply to your P8 specific question, but bear in mind the the Nimrod had Boeing doing a lot of the internal work and when that folded, Boeing took their knowledge back across the Atlantic.