ABM-

Adding a string loop does not get you extra draw length, and neither does using wrist strap caliper release.

Those two items simply move your anchor point of your hand back further. The draw length of the bow has not changed one bit.

Weatherby is talking about changing the actual draw length setting on his bow for a longer powerstroke. But adding DL just for more speed at risk of going longer than your ideal DL in not always a good idea. You'd be better off (and more accurate) shooting slower at your ideal DL rather than faster with a DL that's not correct.

Best of luck-