The Ninja at SFSTL is a custom coaster by Vekoma. It was originally designed for SFSTL but was first assembled in Vancouver for the World's Fair and then was later moved to SFSTL. There are ton's of custom coasters by Vekoma. Go to http://www.vekoma.com and click on product showcase and then product reference list at the bottom of the page. The reference list list's every ride that Vekoma has ever made and where it is located.
The Amazingly painful Ninja at SFOG is an original design however not for Six Flags. It was originally designed for one of the pier parks in New Jersey. I believe that it was bought by Morey's and they decided to sell it.
It operated there as the Kamikazi and was then moved to SFOG where it became the amazingly annoying Ninja.
There is an costum SLC.And the're some MK-1200 MK-700 and MK-900 costum desinged coasters.In 2002 Vekoma will build the biggest inverted.With a loop of 60 M and a height of 80 M.It will be build at Fantasy island (UK).
Vekoma have three woodies to their credit (Holland, Demark, Belgium) They did as well some minetrains, the largest is to be found at Phantasialand, germany. It features three lifts. There you find as well one of their enclosed coasters with three lifts as well. all these designs are custom.