Custom down pipe... can you please help?

[insanekiwi]

Hi guys,

i am trying to get a custom down pipe made in New Zealand, and trying to get a bolt to bolt diameter at the flange... the muffler place says they are likely to have a 3" flange, but would appreciate if I can get the bolt to bolt diameter at the turbo joint (not the cat)...
Cat would be good to if there are any bolts on that side.

I believe there are 4 bolts present... at the flange..

thanks in advance!