When I did mine. I removed the O2 sensors first so that I wouldn't have to fight with the manifold/cats on the ground moving around. I did what you did. Remove the manifold and cats as one unit.
The right side took about 45 minutes from removing the old and installing the new.
The left side took awhile. My heat shield did not want to come out. That took most of my time. By the time I finished up the left side. My hands looked and felt like they went 15 rounds with a pisssed off alley cat. With all of the screw ends, bolt ends and bracket corners on that side. I had about 4 hrs total on this side. With breaks (for band aides and drinks) pushed it to about 6 hrs.
Did you start it up without the exhaust hooked up? Lets just say that one neighbor called the cops on me.
The red JetHot coating looks good.
Hopefully you get that valve cover fixed.