so theres still a leak?

and the band clamp, you did it wrong. you put the clamp on the rear header then put the cross over pipe in.

when the engines cold, fire it up and use your hands to feel for the leak, hot air is a dead give away.

and next big question is did you use the manifold gaskets sd sent you? or reuse the metal factory ones? cause the metal ones are the best and are reusable. sd ones can leak.