The bottom line is, 5 gpp is the IBO standard. Shoot below that and the majority of bow manufacturers will void the warranty. String add-ons don't factor into the equation, other than resultant speed. For hunting, 5 gpp is very (too) light, IMO. For 3D, many shoot at, or near, 5 gpp. I doubt many, if any, shoot that light indoors. As stated above, a heavier arrow does allot to help quiet a bow.