Hi-Flow Cats too loud!

2fast4thelaw

It sounds great at idle and start up but when you stomp on it, it really wails! Its really freeking loud when I floor it. It sounds like a crotch rocket!

The funny thing is its louder inside the car with the windows up. It drones a little with the windows up but not at all when they are down.

The Stillen CB sounds awesome with the stock cats so I am probably going to put them back in.

Hindsight, I wouldnt have bought the HFC's

My Stillen Cats may be up for sale.

6MT

Yeah.... isn't it great?

__________________
Andrew

2009 370Z Sport/Touring 6MT sold
2013 Honda Civic Si coupe D/D

FricFrac

Opposite for me - idle is weak - way to quiet. Sounds fantastic under load. The drone is around 3-4K RPM and its because that's the resonant frequency of your cabin - open the windows and you change that resonant frequency (somewhat). It doesn't matter what exhaust you have you'll get that frequency where it "throbs" like that.

Just a question - if you don't like the exhaust note why did you get a loud exhaust system? The NISMO exhaust should give you better flow and its much quieter. IIRC someone is getting rid of their NISMO CBE because its too quiet.

__________________
'09 370Z - '93 300ZX Vert - '83 280ZX - '83 280ZXT -'81 280ZXT stroker - '72 240Z - Stillen CBE, HFC, G3, Grounding Kit, Sways // Swift Spring // H&R 15mm // 5% Tint // Clear Bra //

BerkTech

Agree with you on that one. The Nismo exhaust is what I would describe as "the exhaust the Z should have gotten from the factory".

Nismo exhaust w/ Berk HFC's. Minicobra's car.

__________________

While the others type fast... Berk Technology goes fast.... See you at the track!
OUR NEW PHONE NUMBER: (714) 546-BERK
READ THE BERK BLOG HERE

Sonic370Z

That would be me!

370Z Nismo Catback Exhaust


Agreed, if you are happy with the HFC's and want to keep them, but looking for a quieter exhaust note, check out the Nismo. Guaranteed to be quieter than any aftermarket setup. I don't have videos of mine, but the user Minicobra1's YouTube videos are what convinced me to go with the HFC+Nismo combo. He has 2 vids on YouTube if you want to check it out.

In the end, it was still a little too tame for me. In fact, I took the Nismo muffler off and ran it for a few hours with only the resonators installed and it sounded FANTASTIC. But I like loud exhausts, haha. Anyhow, definately worth looking into if you want to retain the HFC's. And if you're interested in the Nismo, I know where you can get a like-new one for a good price.

2fast4thelaw

I loved the sound of the Stillen exhaust from the clips I heard. The HFC's radically change the exhaust note. I am not changing out my exhaust system, thats like throwing the baby out with the bath water. I am just not happy with the HFC's It makes the car sound ricy. Plus I doubt I will pass emissions when I have to test car in the next 3 years with the HFC's. Plus I dont like the hiss the HFC's make. It makes it sound like I have an exhaust leak. I think my HFC's need to go.

Modshack

Yours and similar posts have pretty much convinced me to leave the CATS alone. I think the Stillen is a tad quiet, but is a comfortable system when traveling with no bad characteristics. I'd be kicking myself if I made the change and then did not like it...

__________________

Steal my car! (SOLD)...Now Porsche Cayman S
Oil Cooler DIY: Here!

6MT

I must say by reading all the negative posts here, that I'm kind of disappointed. A lot of people (by far the majority) talk about "modding" their cars. With just a little (and I mean a small amount) of research, one can find out loads about what the different mods will accomplish.

I was the same way. Some pointed questions, a little research, and finally... the big decision was made.



Nah, I've decided not to continue. I'll get flamed too hard.

So people..... my experience was to do the Stillen HFC's, CBE, Gen II intake system, and sway bars. I was surprised with the sound's "loudness". Yes, it's not quiet. But the performance gained far out weighs the "inconvenience" of the sound. I really like it. For those of you who are having trouble with the authorities, all I can say is I feel for you. Where I live, there's no such bother when we've got Harley's and the like driving around with what sounds like no exhaust at all.... the 370 sounds as quiet as a Honda Fit.

The HFC's (and the whole exhaust system) "resonate" at different revs. Cold starts are LOUD. Some speeds (read: revs) are uncomfortable (read: droning). But, I took a four day trip with the car and was very surprised at the level of comfort (sound wise). The audio system would generally cover up any exhaust notes when I wanted it to. After that, the rolled-up windows did wonders.

__________________
Andrew

2009 370Z Sport/Touring 6MT sold
2013 Honda Civic Si coupe D/D

m4a1mustang

Same for me... for now, anyways. I ordered the FI CBE with 18" resonators, which I'm thinking will be loud enough for me. If not, maybe I'll add HFCs... but only if I'm sure it won't be obnoxious.

__________________
- Steve

Zs & Coffee - Saturdays at 10AM in Fairfax, VA and Columbia, MD (Click the banner!)
LIKE us on Facebook!

2fast4thelaw

HFC will not make it obnoxiously loud unless you are WOT all the time. If you drive normal speed limit and keep your revs under 3k it's not that loud.

The HFC definitly make the car sound modified and that is what I didnt really want. Its not a bad sound by any means, it just isnt refined like the exhaust note of like a Porche or something. It sounds like a tuner.

Now I would tell anyone who is considering test pipes it will border on the obnoxious loud side and will sound raspy. Even with the HFC's there is a little rasp at WOT but test pipes would amplify this.