The only thing I would say is that an inlet plenum needs to be designed on a flow bench to give equal flow to all cylinders. If this has not been done and more air gets to one particular one, then unless you have an ECU that can trim fuel for individual cylinders, it will melt . The Swedish ones that I sell have been tested on an engine dyno and flow bench to get the optimum spread of air between the four cylinders .

Regarding the alloy plenums that have failed, these have all been inferior copies of the Swedish ones. There has never been a Swedish plenum supplied by me that has failed in any way, shape or form .