I also read the Jet and read about FC. FC claims their manufacturer upped the price or something like that and obx could make it at the same quality for less. I have an OBX header and its a quality piece. The money i spent i feel satisfied with what i have. My car sounds awesome and runs great. I would recommend it to someone wanting to save a few bucks. The gains, i think you will see more torque from the 4-2-1 header and more high end hp with the fs header.
2001 Red ZX3 5spd
OBX 4-2-1 Race Header; Borla 2.5" SVT Catback; MAC Short Ram; FC 65mm TB; FC Race Shifter; Gear Concepts Aluminum Pedals; Painted Interior; SVT Front Bumper and grille