what is the difference between the 12a and the 13 b exhaust port/flanges i dont see much difference

they're almost exactly the same. You can fit the 12A onto a 13B if you open the 12A holes a bit. HOWEVER the exhaust ports will be offset to the exhaust manifold.

the 13b is 10mm longer in the rotor housings, so the exhaust ports are slightly further apart vs a 12a



mike

so do you think i could cut out the web between the ports on a 13b turbo header and push it together so it fits a 12a and weld it back up so i can have a turbo manifold for my 12a

yep

Yeah it can be done, but why bother flanges are cheap buy one 19.00 - 43.00 and that depends on the thickness of the flange you want

well its is far simpler to use a turbo mamifold that has already been made than to make it all out of scratch i knoe i could make one but is a question of why should i if i can buy one