Started this week, I hope to get all the parts cut then take note of all the measurements etc for future reference, I'll be making these from 127mm up to 196mm diameter from around 3 litre up to around 8 litre with a few different designs
Those look like good wide pipes, couple of years ago the racing company next to us had an issue with an engine losing oil pressure on hard acceleration, due to unsuitable size pipes, is all I have to say.
Larger diameter pipes resolved these issues, they occasionally get an outsider to look at their random problems, that's me.