Forgot to mention that these are being made by a group of guys not affiliated with Tyco/Mattel. And the only problem now is how well these pieces nest with 9 and 12" pieces. They're working on that, when that's done they'll start making them.
Makes you wonder why Mattel didn't see the Tomy turn variety, and try to make these themselves to make their product more competitive to Tomy. With all that Tyco track out there in the secondary market (at dirt cheap prices), imagine how many 6" and 15" turns they could've cranked out.