I would say in general you are better to have a FOC around 7-10% for broadheads. Remember that some setups will shoot a lower FOC just fine. Since you know the arrows you want to use then get them & try them out with the heads you have. You may find they shoot just fine or they may not. I shoot 75 grain muzzy's on ACC's 3-60 with 4" vanes. my FOC is way low but my bow is tuned & shoots them great. I had both 100's & the 75's & they both shot great.