2008 350Z Enthusiast 6spd. Nismo Exhaust, Berk HFC's.
Everything was fine. It sat in the garage the whole winter. I drove it every other week to keep it running. Everything was fine, then one day I started it up and it sounded strange. It sounds like there is an exhaust leak coming from around the cats, or y pipe region. When driving it, it sounds normal after around 3,000 rpms in any gear, but otherwise there is a strange raspy low dirty sound coming from the exhaust. Anybody have an idea on what this could be?

BTW. The exhaust was put before I drove it off the lot. The cats were put on last summer. The car only has 10,000 miles on it. The cats maybe have 1,000 miles on them, and the exhaust 10,000.

 

1- small animal made a home in your exhaust.. more common than you think.
2- low dirty noise ( those can be good if theyre comming from a 22 yr old girl) but not sure where yours is, so maybe a floorboard rattle commom in that area when cats gets installed
3- A crack in the hfcs or what have you would make a sputtering sound or a more high pitch sound, moreso under load.
4- is your idle steady and at the proper range? Vacuum leak will make you sputter, drop your rpms at idel and make your exhaust lope.

Hope that gets you started.

 

Well either 1 or 3 seem probable. Idling fine. If I didn't hear the noise I wouldn't know any better. And like I said before it was fine then all of a sudden I start it up one day to hear this noise. I'll see what Nissan has to say about this