Does this sound right? Stillen HFC & CBE
 

I got my stillen cats installed and I wasn't expecting any rasp. Stillen CBE has been on the car for a year or so. The cats were used but look great. I'm just wondering if someone with experience could give me their opinion. I've been reading posts about it and have heard people say they didn't have rasp with the same setup but I'm not sure what I'm listening for. Its quwithin I'm gentle with the throttle. Any more than 25% throttle will produce sound at about 4600rpm. 50%+ throttle will produce the noise at any rpm


Also wondering if a y pipe will help. I also read that the stillen y pipe isn't the best choice. Any input is appreciated. I also hear some noise while decelerating around 3k that is not in the vid; to describe it i would say it kinda sounds like an AC hissing sound. I may try to get some driveby vids if I have time today. Thanks

370z w/Stillen HFC & CBE - YouTube

UPDATE: THANKS for all the help. Im convinced this sounds like it's supposed to and I LIKE IT.

high flow cats and test pipes make a noticeable, hiss-like sound when the throttle is allowed to drop. from what I've read, they make the sound at certain RPMs also. the video sounds completely normal to me.

Definitely sounds like rasp. You could try and wrap your pipes with header wrap for a cheap fix. I would say get a Motordyne Y pipe and resonator, but that will cost you at least $400.

Added info: the installer said he did not install gaskets between the headers and cats bc they weren't needed.

This may also be an issue.

Exhaust leak does sound like that, like a ticking sound. I would try and get an audio sample of that area, also where the Y pipe and cat mate would be good to check as well.

HFCs + Stillen CBE is definitely a raspy combo. I remember way back when 2theextreme had this setup and his car was raspy like no other.

Regarding the HFC/Header connection. You might not need a metal gasket but you should use some sort of gasket material. Tony from Fast Intentions recommends the use of high-temp RTV silicone at that connection.

I'd definitely listen a little closer with the car at idle and with the hood up. See if you can pick up on leaking sounds at that connection. Have someone slowly rev the car for you, too.

That said, I think it could just be normal. Stillen + HFC is pretty raspy.

FF to 0:55

Thanks for the help all.

Heres the best i can do on new audio atm. You can hear the rattle from 0:10 til about 0:14 but I need some help to see if both cats sound the same. It is MUCH more distinct while driving, like in the first vid, and will do it at any rpm with enough throttle. This may be evidence suggesting it is normal but if u don't know it's "right" then it sounds "wrong". I want to make sure there are no obvious issues with the install or cats. Also i found posts discussing the same issue with the same setup, im which ppl have said they hear zero rasp and rattle.

I can deal with it if it's normal, but will try wrapping it and will get a Y-pipe if it helps. Or would consider resonated cats down the road. I need someone to drive by or next to me bc all I've heard is from inside the car.

370z stillen cbe hfc - YouTube

Hiss/rasp is going to be abundant with this setup, however it almost sounds like you've got a bit of a leak somewhere.

Well after several more hours of research I feel like I have a good install(minus some RTV), but Im gonna get a someone to listen for leaks to be safe; and ive decided that i should drop some cash on a resonated XYZ. Also, in case its not common knowledge, i did learn that 350 y pipes will fit 370s but there is high demand for an xyz on our sister forums as well so i dont expect to find a used one.

Here is a great clip I found at myg37 and Cain said his interior noise sounded the same as mine.

Resonated XYZ.mov - YouTube

Thanks again everyone, ill sleep better for sure.

The Y pipe is awesome. It really helped a lot with the PPE headers which sound like a pair of maracas in a fapping competition if not mated to a good exhaust.

Wow Hawk you weren't exaggerating! The difference is night and day between the stillen and XYZ y-pipes. The rattle or rasp that i was hearing from my HFCs is GONE! Thanks again for pointing me in the right direction.

I'll post my comparison video soon.

Glad it worked out :) A resonator at the y pipe is genius because we only need one to tune out rasp from both sides.