Lower letoff cams store more energy. The more energy stored, the more is available to put into the arrow. If you take three different cams that are identical except one is 50% letoff, another is 65% and another is 80%, the 50% letoff cam will shoot an arrow about 3 fps faster than the 65% and the 65% will shoot that arrow about 3 fps faster than the 80%. Just as a rule of thumb, that is, and we all know there are exceptions to dang near every rule.
If there isn' t an exception to a rule, someone will try to invent one.
Question about let off
