I currently run a R32 ECU + Nistune & Z32 AFM and we had no problems setting it up.
Also there is NO WAY in hell you can make an extra 40kw just by changing the computer from nistune to power FC.
I would be finding another tuner to be honest.
He obviously does not understand Nistune very well.
EDIT: Also just make sure the Z32 AFM is a real one not a copy.
But I am guessing its real because your friend has been using it?