You change the type of arrow you use. As stated, 8 to 10 grains per pound is the norm for whitetail.I shoot 55#'s, I use a 550 grain cedar arrow for deer. I could use less but, The bow is much quieter and performs muchbetter. I'm going on a wild bore hunt at the end of Jan 08. I'll move up to a 60 lbs bow with a 750 grain arrow. You do this by either using weight tubes like manboy said, They come in 2, 3, 5, and 8 grains per inch. Which will only increase the weight of the carbon or aluminum arrow, or like I'll do, is use a lamenated birch arrow instead of cedar. There are many hard wood shafts that are excellent heavy arrows. Maple, Ash, Oak, Hickory andLam. Birch are a few. You can ask for a hard wood arrow that is spined for 50/55's and weigh 600 grains bare shaft. Which will give you about 650 grains at 28 incheswhen finished.