Ecko, are those full range pull-ups? I struggle for 10 reps on my second set if I allow my arms to be fully extended on the way down. However, if I lower myself so that my arms are between 90 degrees and 180 degrees then I can manage more reps. Not sure if that made any sense though...
"Never surrender it's all about the faith you've got. Don't ever stop just push it til you hit the top. And if you drop at least you know you gave your all. Be true to you and that way you can never fall." - Tupac Amaru Shakur