While i was reading this whole ordeal, i found it quite funny that he would respond to possible buyers, and positive feedback. Nowhere in there would he respond to joshua. When someone would ask him a question about his turbo kits, he would respond extremely quick. When Joshua would ask him, or state anything about him, there was absolutely no response. I would not be suprised if the guy responds to this, but not to Joshua's post.
I am not the type that is money hungry, or payback ready, but you should get yourself in the safest legal situation you can be. As everyone said, team up and hire a lawyer.