I noticed recently that the K&N Aircharger part #63-1032 does not work with the SC version Xterra. Then as I searched further into the K&N site, I discoverd that the Frontier uses the same part #63-1032 and also has a Supercharger version part #63-1052. Well, being the logical kind of guy I am, I figured if the 63-1032 works on both the X and Frontier, and the Frontier has a SC version in part #63-1052 then that one should work on the X.
K&N wrote back to me saying:
Our kits are application specific and emissions legal so they do not cross over to other years or models. Our R&D Department is in the process of testing this kit for kit and performance.
Huh? Do not cross over? What about the 63-1032? It seems to "cross over".
I guess I will just wait until they figure it out, or some other company impresses me first.