This is something I hear often from people who buy 2550s. The fact is, everyone's opinion is different of course, but you shouldn't really need to change the 2550's stock pickups since they are fine - certainly for hard rock and
heavy metal. The DiMarzio/IBZs are good pickups. If you want to change however, most people go for Air Norton/Tone Zones, PAFs, Super Distortions or, in the case of the
bridge pickup, an Evolution.
From what I hear the SD Full Shred is excellent too.
Good purchase I say - I have had my 2550 for just over a year now, it is an excellent guitar
Cheers
S87