15 pounds of pure muscle in 3 months... may be possible but I'd need to see the receipts *whitneyhouston.gif to believe that.
that's 7 kilograms of pure muscle... damn, I've never seen anyone in my circle of friends pull that off.
Most would be happy to reach 12 kilograms, (26 lbs) over 6 or 7 years...
Unless you're a genetic freak like Darth Wufei (no disrepect intended, but you're fucking amazing)