When I purchased my 1988 C4, the headliner was drooping. That made the 600+ mile trip home a little uncomfortable.

So, I definitely needed to replace the headliner. The factory headliners tend to droop and fall apart over time and they are rather thick which means that you lose some headroom in an already small car. These factors led me away from buying a replacement headliner from the GM aftermarket. Instead I went to my local fabric store and purchased some foam backed fabric.