The TRUTH about aftermarket exhaust drone
 

Other manufacturers are probably guilty of this as well, but FI is the one I (now) have experience with, so unfortunately I have to pick on them. I just had a FI catback with 18" resonators installed two days ago. Despite claims all over this forum this system has drone and a lot of it. 7AT drivers who leave it in D will find themselves in the tallest gear most of time - pressing the accelerator in this situation (but not enough to force a downshift) will bring on drone like crazy, turning the interior of the car into a low-frequency resonance chamber! Some people may not care about this, but the fact remains that all the claims of "no drone" are not true, and I wish someone had made this more clear around this forum - it would have saved me a lot of wasted money. So new people researching an exhaust for your 370Z and considering Fast Intentions consider yourselves warned.

For those who care or later find themselves in the same position, I want to let you know the answer to this problem is that Fast Intentions (and possibly other manufacturers) are building their exhausts minus a very important item - a Helmholtz resonator. This type of resonator attaches to the main pipes at a 90-degree angle, and is capped on the end. The shape doesn't matter (J shaped, etc) as long as it's the proper length - basically what you need is to know the frequency of greatest drone (say 120 Hz for example) and then shoot for a resonator that is 1100 feet / frequency / 4 in length which gets you a tube length which will have a natural resonance 1/4 of the wavelength of the worst drone. Since this tube is closed on the end that doesn't attach to the exhaust pipe no exhaust really flows into/through it, rather a standing wave is established (like when you blow over the top of a Coke bottle) which cancels much (or all) of the drone. Similar to noise-canceling headphones in concept.

Why FI and possibly others are leaving this out? I'd guess it's the inability to determine the proper frequencies needed since the catback may eventually be combined with other items like an HFC, different exhaust header, etc. Thus what would work with stock cats and headers wouldn't necessarily work (at least as well) with aftermarket replacements of these items.

My beef isn't so much that they leave them out, it is that so many fans of FI in this forum make FI exhausts out to have NO DRONE which is absolutely nonsense as I can tell from having it installed two days ago. At a minimum people need to have REAL information before blowing 1100-1200 dollars on an exhaust that can induce headaches or at a minimum be highly annoying. I'll probably get flamed for this since FI seems to be so well regarded here but I wish someone would have warned me before I wasted money having this installed and now will be paying labor charges again to have the stock system put back on (or to have Helmholtz resonators welded on) plus loss for restocking fee since the exhaust can't be sold as new anymore.

For the curious who want to see the outcome of the calculation above, for a drone that is worst at 120 Hz here is how to get the length resonator needed to counteract it:

1100 / 120 / 4

= 9.16667 / 4

= 2.29167 feet

(times 12 for inches)

= 27.5 inches for the length of he Helmholtz resonator tubes

I think everyone is pretty aware by now that you're not happy with your exhaust (as you've posted this in several threads already). It's a matter of taste. The majority of us love the sound of our FI exhaust.. you dont. Get over it or sell it already.. but please.. quit bitchin about it!

I dont see how with the countless videos you didnt pick up on it either. Quit blaming us for your problem.

We know....we read your same exact post in your other thread

Videos can't/don't pick up on the fact the interior of the car becomes a low-frequency resonance chamber. And with people claiming in nearly every thread (and in fact on FI's website) that their exhausts have no drone at all, it's easy to feel misled about it.

A public service that might save someone some aggravation and money. It's pretty clear FI is being less than fully forthcoming since I think their site even claims no drone.

If you guys don't want to read it don't come into the thread. As you can see I predicted this response. You guys are too predictable.

Yea dude, get over it. "Oh man, my aftermarket exhaust is loud and drones in a car notorious for such."

No one cares

If you werent so naive while reading about exhausts, then perhaps this wouldn't have ever happened.

You clearly are picky about exhausts and should've known this. The stock exhaust was perfect for you.

You have an interesting definition of "naive" if it includes reading and believing FI's own website plus nearly every review/fan on this forum who almost universally claim "no drone". You might be OK with that but people who don't want drone shouldn't be.

Guys, to the very least, this is good knowledge. Some people care.

However OP, you may wanna change the title to just say "Truth about drone" as the current title suggests a direct attack on FI, and that's not the right battle

or maybe thats why im not an idiot and always kept a stock muffler on my car.

If you watched videos of this car with different exhaust setups and such, its easy to see that being THAT loud, will absolutely come with drone.

Actually I'm looking at exhaust right now...so for everybody else other than OP, y'all are saying FI has lots of drone now?

I think that's the issue here...he kept reading ppl singing "no drone", then when that's not the case, he's being called stupid for believing other members?

Let's be a little fair now.

Disclaimer: I've never met OP despite being in same city.

Then why not just say as much in the reviews on here and on FI's site? Why misrepresent the situation and then expect people to be OK with it when they find out differently?

A fair point, but do the ther makers claim "no drone" also?

It just varies from person to person OP, I like drone/ deep growl noise thats why i went Non Resd CF CBE with TP even though being this setup while cruising its like stock....some ppl here in the forums go LTH with my same CBE etc etc....I believe maybe for your pickiness you have either stayed stock or gone nismo, just my 2 cents. But I do agree though you cant blame us for what we picked and liked and gave out info on the setup we F.I Customers picked.

Take away on this..."drone" or "no drone" is now a subjective opinion

Yes, apparently drone was bad (since FI's sales/marketing and reviews praised the supposed lack of it) and undesirable right up until I didn't want to pretend along with them. Then drone became fun?

A person only needs to do a quick Internet search to see how many thousands of people in various forums are looking for ways to get RID of drone. Dynamat on every interior surface, spraying rubbery insulation on the underside of the wheel wells, drilling holes in their exhausts to add the resonators I discussed in the original message. It's pretty clear drone is bad and few like/want it.

Wow just got done reading a couple of your other posts. Three things come to mind.

1. Sell it super low milege FI CBE should be easy to sell.

2. You might try to ask Tony about fabbing something up and you will be the test Z for him. Not sure flaming the **** out of FI is a good start on that though. Sounds like you have done some research and know what freq you are looking to cancel.

3. You can wait for me to get mine and I'll sell you my stock nismo exhaust #834 so about another month or so.

One other thing, you know you have a peice of art in the FI exhaust

hope it works out for you though

As long as I have been modding cars (which isnt as long as others) and adding aftermarket exhaust "drone" has been subjective. This isnt new information here. To me the GT Haus setup I had, had little to no drone with a slight hiss on decel. That hiss is a deal breaker for most, me, didnt care. Some people who watched my videos thought it sounded awful.

My 3" F.I non resinated exhauast had even less drone if not any. Maybe the turbos helped the issue. Now this Zele Exhaust makes me mad at times but it is super rare and I do not drive much. So someone in my shoes I would still recommend the Zele system to.

My "take" on this is do more research and dont blame people trying to help when you do not like the product YOU decided to purchase.

I think the people that love their F.I system in various configurations say enough.

In the interests of being fully honest in looking at FI's site I have to admit they do NOT claim "no drone" (reviews here almost universally do though). What their site says is "no rasp" which is true; their comments on drone state that the larger resonators have less, which could well be true but the 18 is the one I'm familiar with so can't say. But that type of inline expanded section isn't apparently how you effectively get rid of drone if the Helmholtz info is to be believed (and it should be since there are lots of examples of people resolving drone with them). The Helmholtz method requires the resonator to be 90 degrees off the exhaust flow, not inline with it.

Did it ever cross your mind to try and find someone with a FI exhaust so you could hear first hand? I know before ordering my exhaust I did some pretty extensive research... not just reading posts on a forum. You may have read multiple places the claim for no drone but didn't anyone ever tell you not to believe everything you read on the internet? :shakes head:

drones lol
 

http://i249.photobucket.com/albums/g...ETS/drones.jpg


http://i288.photobucket.com/albums/l...org_corpse.jpg

http://i303.photobucket.com/albums/n...uddy/borg3.jpg

http://i236.photobucket.com/albums/f...ayter/borg.jpg

I did listen to some though from outside the vehicle (idle, revving). You're right that I should have taken some extended rides, but the opportunity didn't come up. So my bad there, for sure.

As for the reviews, another good point. I just figured I could trust the preponderance of reviews of an exhaust for 370Zs on a forum dedicated to that car. My bad?

Fact is FI is a small company and a lot of people may live in places where no reps that sell FI are, or have anyone near them with the exhaust that they can to listen to. In those situations the reviews here and elsewhere are largely what people use to make purchase decisions.

I have read through the two pages and am putting together my response as we speak!

Tony

I never drive my 7AT in D so its not an issue for me, although I agree with the OP. Having said that I spoke with Tony at length prior to purchase and went with 18" resonators to minimize it. This was his recomendation for me based on my expectations, to reduce drone. He never claimed there would be none. I'm totally satisfied with my purchase and service from FI.
OP did you discuss this in detail with Tony prior to purchase? :ugh2:

I've had several chats with Tony, yes including one by email just after I got the install done Monday. I also started a thread on the G35 forums (I owned a G35s and a G37s after that) discussing the desire for before/after decibel measurements of FI exhausts and had discussed their exhausts with Tony around that same time. I chose the 18" on stock cats for that very reason (quietest option). I just got a lot more drone/interior noise than I expected or was comfortable with.

OK but you weren't expecting no drone at all as you originally stated. It is a subjective thing for sure and as mentioned earlier you'll have no problem selling it if you choose to. Good luck! :tiphat:

Yeah, just sell it and move on, OP. I don't see a real legitimate reason to slander a stand-up guy or company like F.I because you didn't like the taste of their Cheerios. Not one company can make everyone happy with a product even if the vast majority of its customers love it.

You did provide some good information, though. I give you that.

If u think interior noise on the FI is bad you should try the Motordyne ..

Yeah no intent to cause FI or Tony a problem - just frustrated with the expectations created by somewhat misleading info in forums/reviews and the hassles/expense of needing to have more work done now to put the original exhaust back on based on it. And it's such a solvable problem - that's also frustrating. Why settle for any drone when it can be eliminated simply by adding 5 bucks worth of two steel pipes onto the exhaust (is what I'm thinking/feeling)? As I mentiomed, I understand partially it not being done due to them not knowing what cat/header you'll be using. It would be nice to offer a catback tuned for stock cats/header that included this drone-free Helmholtz option. It might become their best seller.

Ped,

First and foremost let me be the first to apologize if you are unhappy with the result of your purchase. That being said I feel that the tittle of your thread is misleading and unfair. You need to understand that sound is subjective and everyone perceives it differently. What may be loud and have drone to one person may not be loud nor have drone to another! Not anywhere on my website page do I state the exhaust system has NO DRONE. I state that it has no rasp and that may actually be a little misleading. I should state that certain combinations have no rasp! I will be sure to change that shortly.

Now let it be known to everyone who reads this that you DID NOT purchase our exhaust through us. You purchased it through a third party vendor and I have no control how the purchasing process took place. I have no control how you were informed or educated on the options available.

I can tell you that every single one of my systems that I sell, I take the time to go over every option with each individual customer. I have been doing this a long time and have sold nearly 900 units for this car. For you come up with a thread like this now is a little unwarranted and ridiculous in my opinion. You are clearly have a bad taste in your mouth over your buying experience with the vendor and are directing it at us, NOT COOL! You should of resolved this with them in a private manner opposed to attacking us on a subject where subjectiveness of sound plays the main factor.

There are 100's of reviews out there. Here on the forum, on our website, YouTube, ect... I have hundreds of satisfied customers running different combinations for this car. Are there unhappy people out there who may have buyers remorse, sure but that has happened to all of us at one point or anther in life. You cannot make every single person happy however we try. At the end of the day I know our satisfaction rate is in the high 90 percentile.

Now you emailed me Tuesday 9/17 and stated that you were "regretting" your purchase. I took the time out of a courtesy to email you back in detail in response. Now I could of just told you to deal with the shop you purchased it through because you were not my customer. However, I took the time to go back and forth in emails with you answering all of the questions you had for me. After all, it is my product. I explained to you much of what I wrote above and that the interior sound should dissipate roughly 10% once the resonators broke in and had some mileage put on them. You emailed me back stating that the combination you purchased was our quietest however not quiet enough. You asked if I had a quieter muffler to interchange. I responded with saying that unfortunately we do not have a quieter option than what you purchased and every once and a while our quietest option is just not quiet enough for some. I closed by saying the best thing to do moving forward was to contact the shop you purchased our exhaust through. Again, I will state if you feel like you were mislead than I do apologize. Not at any point did it come from me nor anyone from Fast Intentions, Inc. You can ask anyone who has dealt with me or my company. We take the time to make sure every single customer is satisfied and comfortable with their purchase!

All of this being said, I am more than willing to take time out of my schedule to talk with you over the phone. Even though you are not directly my customer, I would like to hear your side of the issue one on one and see if there is anyway I can help.

Thank you for your time.

Tony

I can tell you there's no drone above 5000 rpm! Ya baby. :happydance:

Not to stir things up even farther (is that possible?) but you don't even have to look far to see hat I'm talking about in this thread. Right near the top of the intake/exhaust section is this thread. In it the OP is asking for a catback that has NO drone. He even emphasizes that he "hates drone with a passion".

http://www.the370z.com/intake-exhaus...ast-drone.html

The *very first poster to reply* proceeds to tell him that FI catbacks (in all their combinations) have "no drone" and are a perfect choice for him.

There are already a number of threads about hemholtz resonators already, nothing new introduced. HKS, ARK Grip, and Motordynes exhausts use em, even maybe a few knock offs. I don't see a reason for F.I. to add it on their exhaust, or any other exhaust manufacturer to theirs if they don't use them. The stock exhaust doesn't have one, and guess what? No drone. It's not an oversight because it's not being used, it's just another option.

He says drone is subjective and that it's perfect for HIM, it has nothing to do with what is advertised by Tony or anyone at FI

OP, sell the exhaust, you'll get what you paid for it because people don't want to wait.
Now the install/removal cost, you're SOL.

And if you think the Hemholtz resonators will work, why don't you add them to the exhaust?

Ok, you are failing to realize something. First off, a consumer posted that. Second, he clearly feels the combinations do not drone. This is a case of subjectiveness just at the other end of the spectrum. Now as you are doing your research in the pre buying process it is your obligation as a consumer to read through what is accurate, what may be accurate and what is not accurate. If the general consensus is satisfied with their purchase however you are still not convinced, than don't buy the product. Wait until you can hear the combination you want in person before jumping in.

Thanks, Tony

Btw, there are enough members in Dallas with the FI exhaust, so you should've gone for a ride. And I know one has an auto too, although I'm not sure if he'd give you or anyone a ride.

I suggest FI products not for sound because that's subjective, but I recommend their products for Tony, and FI's relentless pursuit of perfection when it comes to build quality.

Thanks for replying Tony. If you acknowledge (as I do) that you make no claim that your exhausts have no drone, then I'm not sure why the thread title is an insult or a problem. But I can change it if that's possible to something else.

The main issue is with the misinformation so prevalent on here. After chats with you I knew what your quietest option was. After that the rest of the info necessarily comes from videos, reviews, general posts on here, and finding people's systems to listen to (something I already acknowledge I didn't go enough of). The fact I can look two threads below this one and find someone blatantly suggesting FI exhaust have "no drone" whatsoever to a guy specifically stating he wants none and "hates drone with a passion" speaks pretty loudly to what I'm referring to. I know you don't have control over what others say on here, but you are pretty active. I'd think if you really wanted to quell that type of thing that a few visits from you into threads like that, to set people straight, would have people producing more accurate information. So you should accept some responsibility for allowing this type of misrepresentation to go on. Maybe it's been good for business and you looked the other way, but it's not accurate. And you shouldn't cry foul when I start a thread calling out bad info that you (presumably) agree is incorrect.

My options at this point are to live with it (not likely due to what I estimate to be 100 db+ of low-frequency harmonic resonance drone in the interior), pay someone a couple hundred to manufacture Helmholtz resonators, or return it and accept the loss of some money for trying out something that didn't work out. I would go with option 2 except for the unknown outcome of how much drone would actually be gotten rid of...

I'm #1 on the list with the 12" resonators. Yes, there is some drone between 2-3k RPM, but I don't hold the pedal at 50% in 6th gear between those RPMs.

If it helps... turbo and test pipes seem to make it a quieter option. ;)