[SA-AUII-MAX]

Thanks guys for your response. Yep I’m quite sure it’s pinging because during the dyno tune while setting up the engine it made similar noises. Each time we made corrections preventing it knocking, only to find out that it starts to “ping” later again. This pinging or knocking is sometimes present when I put the pedal to the metal from a standing start. Weather conditions apply though, the warmer and drier the heavier it’s starts to ping. Driving with the aircon on makes it worse too.
I tow a horsebox with the car, explaining the rather heavy load. That cat converters can start a fire in long dry grass I did know, one reason more to take the cat-thing off. And why the cat got smashed?, a big stone in long dry grass. LOL