Man to be honest you bi's will grow how they want to grow. I mean lok at thin kids who have nice peaks. Do you reall think they know something you don't? But heres one thing that may help. I say may because everyone is different. Between the bicept and tricept muscle is the brachiallis(sp?). A lot of people don't ever focus on training this muscle. Training it can help you get a peak if you have long bi's. Causing this muscle to grow pushes the bicept up in the middle. To do this you have to do bicept exercise where the bicept doesn't contract as much but you have to get them to the point where you can work heavy. This takes time (of course). These are exercises like hammer curls, reverse curls, or curl where your elbow is over your head. Give it a shot and good luck...