Paul Jr.'s career really launched in 1980, when he became part of JLP Racing's driver line-up. His first race was at Coca-Cola 400 at Lime Rock. Co-driving alongside his father in a Porsche 935, they won the second heat, and subsequently the race overall. Junior had won the first IMSA race he entered. He repeated this feat by winning the Road America Pabst 500 three months later. With three second places, he would finish fourth in the final IMSA GTP standings.