Ed thanks so much for taking the time to comment. It sounds like both of these measurements (TPI and FOC) operate independently and applying/understanding the limitations and advantages of each is key. I guess until you can convince more people to let you put holes in their prized caped buffalo we will have to wait to see where the sweet spot between the two is. I guess the nice thing is that two of the three TIP variables are fairly easy to meet by using skinny arrows and sharp single bevel broad heads. The real question is where does FOC begin to significantly cancel out the need for momentum if it does at all. I hope your next visit to the inter webs finds you in better health.