I left the idea with thick wall piping...for now.
This time I'm cutting up OEM Harley pipes instead.
The other big job with the pipes except positioning the turbos is to step them down from 1 3/4" to 1", what that the turbos have as inlet.
Did some calculation and came up with I have to shrink the circumference from 139,5mm to 79,8 mm.
To manage that I did 8 triangular slots 7,5 mm wide at the top.
This is just a measuring prototype and the final pipes must have some more massage first for the right angles out of the heads to position the turbos.
Buts that's another post......
The 1 3/4" pipe i started with.
The 1 3/4" pipe with slots.
The stepped down end ready for weld.
And the finished testpiece next to the flange.
Think I´m on the right track here, but I have not abandoned the idea with more rigid thick wall piping.Time will tell wich alternative will walk away as the winner.