First, I found a piece of flex hose from a swimming pool filter, cut it to the runner length I wanted to use in visualizing the placement of each tube. It is a great way to see roughly where the tube needs to go to get the right length.
My design is unconventional by what you see out there, but has a couple of advantages. First, going over the chassis tube allowed a very straight exit form the heads in the first ten inches. This really helps to build power from what I have heard. It also cut down on the total number of bends in the whole header system. The problem is getting enough collecter length, and its' placement.