What would be the maximum boost pressure that could be achieved in a gasoline engine with one or more turbochargers, assuming the engine can withstand it?

Here in Hall 77 they are talking about 4 bar boost pressure: 18:43 https://www.youtube.com/watch?v=2FceDSkUnVo How low does the compression have to be to prevent knocking combustion?

Opel Corsa OPC 1.6 2008 boost pressure control valve defective fluttering noise?

Hello, I was driving my car recently, even driving a bit sportily. When I got off the highway, I stopped at the traffic light and didn't think anything of it. Then I drove off. First gear was useless, and in second gear, at 2,200 rpm, when I shifted to third, or when I let off…