stainless steel vs aluminized steel, mandrel bent vs regular bent

I was considering headers but with my j heads I was thinking i might want to see how it runs with the stock manifolds first.

Plus, the headers I want (super comps) are pricey. Figured I could get the exhaut done and then next year go for headers if I decide to go that route, just cutting at the cross member and then patching back in...but yeah, I know that it probaly wont be that easy...LOL