Hi guys i have a g37 coupe with xforce catback and empire performance resonated test pipes (both australian brand so you might not know of them). My friend has the same testpipes with invidia exhaust and he doesnt have this problem. Its very noticeable both standing and driving. Any help would be appreciated.

https://youtu.be/Rme5KnbHaNA
Video 2
https://youtu.be/Xe6q-VaOG0U

 

Do you mean the hissinng noise when the rpms are coming down? Like it goes “vrooom” then the “psssst”, you mean the “pssst” sound?

If so that’s 100% normal for every car I’ve heard who changes their cats. Some exhausts are better than others at reducing it but they all do it to some extent. I know people have added more resonators to soften it but it’s all guesswork really.

That noise is why I haven’t changed my cats to be honest. Your just going to have to live with it. Search the forums about where people put in resonators to try and soften it, I saw some thread about it not too long ago. That’s the best you can do. Don't put race car parts on your car if you don’t want it to sound like a care car, lol.

 

as Sobe mentioned, the 'hiss' is normal with our motors. exhaust systems with larger mufflers are better at covering the hiss. I had a little bit of the 'hiss' with my Top Speed exhaust and Motordyne. When I added Motordyne ART pipes to my Motordyne exhaust, the 'hiss' went away. Now that I have a single exit, the 'hiss' is more prevalent.

 

Thanks guys, thats a bit of a relief. I looked up online and asked a couple of friends with VQs and yes they all have it haha. Its not as noticeable on their cars as their exhaust is alot louder. So my question is that how do i make my exhaust louder and deeper without worsening the hiss? I have 2 small resonators and a large muffler on the exhaust, was thinking of doing a delete on either of those. Would you recommend this?

 

Btw here's an acceleration video and that hiss/rasp is so much noticeable all the way through the rev range. Especially noticeable between and after shifts. Is that normal?