Originally Posted by Armhunter

UPDATE!!

Just talked to the guys at FI. From what they told me is the Nismo Exhaust is not built to take that much air. The Test Pipes or even the HFC are allowing more airflow through the Nismo exhaust and it will create that sound. He said once I get their exhaust installed it will eliminate the sound. They said i will still have a small hiss from letting off the gas but it wont be the Rasp that we hear now. Just thought you all wanted to know.