Carpet Pad

Carpet question??? I purchased a carpet kit from Auto Custom Carpets and the padding less than half the thickness of the factory pad that is on the carpet I'm replacing. The factory pad is in very good shape. It doesn't stink or have any missing parts. Should I remove and( it's kind of glued to the old carpet) use the factory padding or just use what came with the new kit?? It's for my 66 cuda.