It really matters how long the head pipes are and how you wrap them. If you wrap them tight, by wetting the wrap, you may need less then if you wrap them with only a 1/4 "overlap" and loose. I bought 2 rolls of white. I really don't know how much I used. The stuff I had left over I wrapped my lawn mower pipes to make it look neat.
I will suggest that you start from the back of the pipes (tail end) and work forward. This makes the overlap lay on the wrap better. If you started from the front, and worked backwards, the overlap lays forward, thus making it catch the wind. After time it starts to roll-up. Looks like shit.