Look up posts from khouse. It's some of his last posts.
Is this the one?
http://www.pinewoodderbyonline.com/threads/k-groove-k-house-groove-kutter-jig-to-all-builders.1146/#post-42470
I currently have several spots available! Several of those that I have worked with have done very well, congratulations! PM me to get in on the speed secrets!