I'm looking to put the final touches on my nitrous kit and I need a Purge kit along with an FJO WBAFR. I'm installing an NX LSX kit, which one of these Purge kits should I purchase? If anyone knows a good place to find a good price on an FJO WBAFR kit, please let me know.

15600 NITROUS PURGE VALVE (D-4 MANIFOLD, PUSH BUTTON, AND VENT TUBE)

15601 NITROUS PURGE VALVE (D-6 MANIFOLD, PUSH BUTTON, AND VENT TUBE)