Very similarly to cars, we archers love tinkering with our bows. In Buck Magnet' s case, I don' t think it is a question of enough power or speed for an ethical kill but more for the sheer satisfaction of eeking that last little bit out of an already more than adequate setup.

Moving the leeches towards the ends of the cable will improve your speed, but at the cost of noise. When the string vibrates after the shot, the largest amplitude is found at the center of the string. Seems to me that if the leeches were placed at the center they would do the most good (from a purely theoretical standpoint). This would also mean the bow would have to drag them over the entire draw length, causing the greatest loss in speed. The farther toward the cams the leeches go, the less displacement the bow has to impart on them and the lower the speed loss. However due to the lower amplitude vibrations they will not be as effective. In all reality you may not notice the change in noise the farther out you go.
If you are in to playing around, you could try to trim down the leeches. Removing mass from the string will increase speed, but this will cost you noise, plus you will chop up a perfectly good set of leeches.

For the peep issue, you could always get rid of the peep sight alltogether and go with a NoPeep or hind sight. That would help remove some mass from your string and give you 5-7fps.

If that is still not enough then you can always look into 80lb limbs