Moosman76 has it right. The smaller stripes are fiberglass. The Phenolic is in the limb wedge continuing on through the riser.
Iron,
I doubt the Phenolic is the reason for the speed difference. That is a non working portion of the bow limb. There must be something different in the limb cores themselves. You make a good point about the mass weight though. That does have me a little concerned since I like the extra weight but I figure I should be able to add a full size quiver to make up for it if needed.
I'll talk to Toby this week and hopefully I'll be able to pick it up in Kazoo so maybe some of you will be able to see it in person. This is the most spectacular piece of would I think I have ever seen. I even got a piece of scrap to make a Knife handle with.
It's like Christmas in November picking out your own wood. Come to think of it it'll be like Christmas all over again when I pick it up