I have a bit of experience here and will chime in: The original JayJay turbo system had its heyday in the 1960's. RayJay as a company was in California, the STC then went to Kelley Aerospace, and then to ModWorks. It is now effectively an orphaned STC as ModWorks is no longer an entity. The STC is not specific to any particular airframe since in those days RayJay did not specify a specific airframe for installation. The original RayJay and the M20 Turbos system are very much the same,
