NISMO 370Z (2009– )
2010 Nissan 370Z NISMO
The NISMO version was introduced for the 2009 year model. The engine produces 350 bhp (260 kW) at 7,400 RPM and 276 lb·ft (374 N·m) at 5,200 RPM with revised ECU settings and exhaust setup. Transmission choice is limited to a 6-speed manual with Nissan's new "SynchroRev Match" function. Handling is improved via stiffened springs and stabilizer bars compared to the 370Z Coupe. Other equipment includes 19-inch RAYS forged aluminum-alloy wheels with Yokohama ADVAN Sport Y-rated tires (P245/40ZR19 front, P285/35ZR19 rear), 14.0-inch front and 13.8-inch rear vented rotors, NISMO Sport Brakes with 4-piston front and 2-piston rear aluminum calipers, and a fully integrated chin spoiler.
Taken from
Nissan 370Z - Wikipedia, the free encyclopedia
So the thing that is causing the differences between a NISMO and a non NISMO + exhaust is the ECU tune, which was what I said earlier. That is why the guy with a non NISMO + exhaust was only getting 5whp, he is missing the ECU tune that the NISMO has.