You may want to put some additional padding behind your back - may be what the "how tall are you" question is leading too. I train w/ a guy thats 5'6" (he thinks he is 5'8" but that is a different story). He uses a pad from another machine - it only covers the lower back region - it helps him and he stacks the machine to it's max (28 plates) and reps it for 15+ reps and uses a full ROM (Dorian would cry). I have even seen him use an entire back piece from an old bench to get himself closer. They are certainly not the most versitle piece of machinery in the gym.