About to pull the trigger on phase 1 of upgrades (finally). HFC's seem an essential airflow upgrade, although I was initially hesitant due to "off road use only" warning. I guess I'll just keep the old ones and bolt em on before I get inspected. Tints are already illegal so might as well go for it huh?

ANYWHO, will the stillen hfc's be obnoxiously noisy? I assume they will not be as loud as test pipes, right? I've listened to alot of video, but it's still hard to tell what mod their noise is coming from.

 

HFC's won't be as loud as Test Pipes, but they're still pretty loud. Expect your exhaust to sound raspier after install.

 

any way to get the rasp to go away?

 

Well I know SOLISIMO wrapped his Test Pipes (Which are raspier then HFC's) with header wrap. It eliminated the rasp on his set up. But I don't think anyone has tried it with HFC's. Not sure if it would have the same effect or not

 

Interesting - that's the main reason I'm leaning toward a stillen exhaust is b/c they seem to yield decent gains while still sounding reasonable. We have a neighbor who has an old accord with a bolted on exhaust and what must be test pipes, and the whole neighborhood knows when he's coming/going. I want her to growl when I step on it, but I don't want to be that guy!

Could anyone link me a stillen hfc/stillen exhaust combo sound clip? That would make my decision easier...

...altho I just might say F it and do it anyway

 

HFC will not increase your noise obnoxiously but it will be slightly louder. AS SOLISMO said, what you'll notice is an increase in raspiness. I have HFC and Invidia Cat back which doesn't have any resonators in the mid pipe. Is it not loud at all. It is very similar to stock in noise level; it has a metallic rasp and the hiss common to HFC when you let off the accelerator, but it's not loud at all. No I don't have any video.

 

Here is how mine sounds with Berk HFC and magnaflow exhaust. I have other vids if you want.


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hfc's will definitely make your exhaust louder:

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Aliiin and Dipstix,

Thanks so much, both were very helpful, and I'm going to do it! The dyno's I have seen on HFC's portray them as one of biggest single gainers out there in terms of bolt on mods. The noise increase is there, especially when u really get on it, but neither was obnoxious in my opinion. The aggressive sound is good IMO - should be more pronounced with CAI and exhaust.

So I should keep my stock cat's so I can pass emission testing right?

 

you should keep your stock cats, but the point of HFC's is that it's less restrictive and more free flowing than OEM cats, they will still pass emissions... test pipes won't

 

Just be careful when installing the cats. One of the bolts has a tendency to break.

 

Yes, you should keep your stock cats just in case. As others have said, HFC's are one of the best single mods you can do for proven gains.

Check out this video taken from a bumper mounted camera. It's a 370Z with BERK HFC's. The 370Z has the same motor, same HFC's, and same stock exhaust as the G37. So this is pretty much what your car will sound like with the BERK HFC's on there and nothing else.

http://berktechnology.wordpress.com/ - it's about 2/3 the way down. Sounds even better in the cabin!

 

+1

Make sure your shop knows what they are doing. You need to handle the O2 sensors (front & rear) with more care than we're accustomed to.

 

anyone tried wrapping the hfc's with header wrap?

 

Some have done it on test pipes but none on HFC's. HFC's quiet the exhaust down a great deal compared to test pipes. Plus, heat wrapping an exhaust part will greatly shorten the lifespan of any exhaust part. Most manufacturs will void your warranty if the parts have been wrapped.