[Spenny_b]

Well, upon crawling under the car and having a good look at the underside of the engine, it looks like I've got to now remove the ****** exhaust headers; evidence of sooting on the fins of the barrels from the dyno session. Despite me measuring that the sealing ring heights were sufficient to seal against the protruding primary that sits inside the exhaust port, something clearly is causing them to leak. Maybe just expansion under extreme load/heat? Of course, I will just check that all nuts are tight first.

Interestingly, when I first bought the car, it came with a snapped header stud on #3 (iirc), so I got a local Porsche specialist to do-the-necessary on his 4-post lift. We noticed that the headers were installed with 2x rings per port, double stacked; seemed odd at the time, but I was told that this is quite usual.

Guess I need to go and get another set and install with the existing ones.....is this "usual"? Seems odd to me.

One step forward, two steps back.