under 5 gpp is where you get into warranty issues, and possibly health issues, lol. It can be done, Quicksilver shoots much lighter arrows out of his HCA bow, i think....but i personally wouldn't do it. Heck i shoot over 7 gpp.

Bump up the BH weight to make you over 5 gpp. It will be a minimal loss of speed, greater FOC and slightly higher KE for better penetration. Double check to make sure the new BH weight doesn't throw off your spine.