So this has happened before but I assumed it was the result of an exhaust leak that I had from my test pipes previously... Anyhow I fixed this and the sound went away but I recently had my nismo cat back split from its weld connection to the y pipe so after I welded that back together the sound came back. It literally sounds like those alien ships from war of the worlds I kid you not an its every time I downshift to slow down around the 3000rpm range. It's pissing me off help
-Nismo S Tune Catback
-Top speed pro 1 test pipes non resonated