Thanks. How do I decrease the spine of my current arrows without adding more weight upfront? I noticed the insert has a hole in it. Can I add a tube or fishing line to increase the overall weight of the arrow thereby decreasing the spine? I've already got 140 gr Magnus broadheads. Do I need to buy different arrows? What do you recommend in aluminum that will allow me to shoot the 140s? These arrows were recommended by someone at the store, so I hope I can exchange them if necessary. Thanks!