Moinsen, some time ago I mentioned that there are obviously 2 different vents on the C20NE. Since I wanted to ask more about a new thread (with new questions ). In the appendix you will find a picture of my built-in housing ventilation (C20NE Vectra A, Built. ’91) and the valve cover, which I now have here (Astra F GSi, Built. ?) My question… the second valve cover from the GSi looks much more useful for me, since only the first venting looks much better for me. I’d like to change my head on the outdated GSi head with its valve cover. Where would the additional ventilation theoretically go, and to what extent could I convert the existing ventilation to the thicker & additional ones? What do I need for parts? I’m grateful for all tips & tricks. Greetings, qp