I saw a tetra vid on youtube and they stated that a rally version had a ejector exhaust system on it that allowed 11;1 compression.
Maybe by using the exhaust as a heat sink for the head?
I wonder why I have not seen anything like this on anything else?
Edit: this is the vid and the particular car is at 8 minutes. The compression reference must have been in a article I read about ejector exhausts because it is not actually in the video. https://www.youtube.com/watch?v=MJBNpfeM700
