I was struggling at Spa a bit for headroom with my helmet on. Is there any way I can rake the sunroof out and put some sort of temporary blank on it for future trackdays, just to give me a little more rom?
Try changing your sitting position a little bit Matt. I find myself needing to adopt a lower sitting position when the helmet is on...i'm so much shorter than you so can't imagine what it must be like for you...oh yeah..now i remember. Your head was tilted to one side the last time
Or if its only a trackday car,then cut a sheet of carbon fibre to suit and then pop rivot it and also use a bead of silicone sealent to cover the sunroof hole.
But you might not be allowed on certain tracks (safety rules) as its not metal or welded in place.