Header removal on my Dart

I'm putting exhaust manifolds back on my Dart. The car had Pypes exhaust on it with headers. The second owner put the exhaust on, I bought it from the third owner, I'm surprised it didn't fall off. Barely on there and not tight. Then to remove the headers, the right side came off fairly easy, the left side wasn't horrible. The guy who put them on beat the crap out of the floor and beat the tubes almost shut. I don't know if it was the right set of headers.