Exhaust
Here we are, replacing the exhaust...or at least the center section.  I got very good at this, having done it three times in a week.  When I bought the car, Steve had fitted a test pipe, replacing the catalytic converter.  Great sound and power, not so great for emissions.  In order to get a tag, I had to refit the cat and get it tested.  The good news is it passed!  Then what did I do?  I pulled the cat and reinstalled the test pipe of course.