Is the coloured lettering and pinstriping on this 1996 Impala SS something that a previous owner added, or is this original?

The 1995 and 1996 (the only two years for this Impala) were totally black in color and I think black was the only color it came in. Some dealerships add pint striping and other decals to stock cars to increase the amount they can charge for the car. Only decals like DEAMON, ROAD RUNER, or 442 W-30 come from the factory. Hidden deep in the bowels of your dealership, are rolls of pint striping of several different types and colors. Look at the small strip of paper to the right of the Monroney label and you will find the mark up.

In 1996 the body colors were black, maroon, and gray-green metallic. Any trim, like that found on the doors (rub strips) and the trim on the rear fenders came in body color. The emblems on the C-pillar were chrome plated plastic, as was the trunk emblem and the grill emblem. There was chrome trim around the windows. The 1994 model was available in black. I'm not sure if the 1996 colors were all available in 1995, but there were only three colors ever offered. Silver was supposed to be available in 1996 but that never materialized.

I know quite a bit about the cars since I bought a 1996 model in 1996 and I was a member of the Impala SS Club. I sold my Impala in 2007 prior to moving overseas; wish I had kept it and put it in storage while I was overseas for a year. I would likely still have it today. It was a very dependable car.