Originally Posted by '10Anamoly

I have the Nismo S-tune and its significantly different than the OEM Nismo exhaust.

OEM Nismo: 1.75" Primary pipes that stay true dual throughout the exhaust. They increase to about 2.25"-2.3" later on down the pipe run near the mufflers. There is a H-configuration crossover near the engine. Flows better than the OEM 370z exhaust but is not as sharp or fancy in build construction as the S-tune. About a 5-6 hp gain max for swapping this in place of the OEM exhaust.

Nismo S-Tune: 2.4" Primary pipes, joining into a single 2.5" y-pipe, then splitting back to two 2" pipes, through two resonators which stay 2" inside then back up to 2.4" out the back and through the muffler. About a 3-5 hp gain max for swapping this in place of the OEM exhaust. It's also VERY quiet.