programmer's?

[black07ss]

So my buddy just bought a 2012 GMC Sierra with the 6.2L  he has been wanting to uprgrade the performance of it so I suggested 1 option would be the programmer.  Apparently he has a couple of other buddies that really don't have any good marks for programmers.  They say it will blow an engine.  I have never heard of this. Granted I really haven't looked into the pros and cons of them, but I have a couple of friends that had them and have never blown an engine.  Just curious what everyone thinks.  Thanks