I also am swapping the pups in my 550
my 550 is pretty bright so i am going with either a air zone or the IBZ/USA series pups for extra warmth
right now it has a duncan custom in it and it is too trebly for me in this guitar
fior you I vote for breeds or tone zone/air norton set in a 550
the EVO 2 like vai uses is pretty good but still a bit trebley for me in a 550 so a traded for a
air norton with another forum member here
you may like the evo 2 though?