I'm probably wrong about this, but I think the tensile strength of aluminum would prohibit its use for headers on a street car. Too much flexing from the rest of the exhaust might cause an epic failure.
Please correct me if I'm wrong.
I'm sure your correct. Even the cast iron Hyper packs have multiple pics of the rear ones welded at the flange. Maybe some sort of rigid exhaust on hangers and a flex connector like the modern transverse motor cars have.
