I had the same problem when I bought a 2001 king cab S/C. It takes the aftermarket a while to catch up. In the mean time you can be creative. Nissan shares many parts with other models, even on a new model. You might find some performance parts swap over.
IN my case the S/C king cab had the crew cab chassis so I changed the suspension out to crew cab which had stiffer springs that allowed me to lower it and improve the ride quality at the same time. It was a tough to convice the Fabtech guys to sell me Torsion bars for another vehicle. I practically had to snatch them and run out the door. They installed and fit perfectly and worked so much better than stock.
2004 4x4 smoke Armada
2005 Mini Cooper S
1994 BMW325iC with goodies