Does this sound like a manifold gasket leak?

The flanges are indeed pretty thick. The pipes were welded decent toward the ports and all that. I was real impressed how easy they went in, they are dodge dakota shorty headers.
Wow man I welded so much on the inside the tube diameter is now only half. Wasted an entire spool of flux core on it and it still leaks. I didnt even find the hole so I went over every weld but this header is unuseable, I contacted the seller to see if I can get a replacement
Alright, I am gonna wrap this up here. The seller issued me a full refund for the headers and I went ahead and bought another set (even cheaper lol) from a different seller. This time around its all sealed and good to go. My engine runs noticabely smoother compared to the original manifolds. I think there really was a Bottlenack. Thinking about replacing the flowmaster mufflers with something like a hooker max flow. Oh yeah I looked at some intakes as well as I have the spread bore with an adapter... intake manifolds are 500 to 600$ now??????? Wow.
Lots of used intakes out there.
If you haven't, watch the engine masters episodes on mufflers