HFC and tune :tup:

Definitely HFC

Hey OP you have a really great setup there if you think its too loud imagine me (never ever purchased an aftermarket cbe) and I purchased Non resd CF CBE and TP hahaha way too loud as a first timer but like a member here said after breaking it in My oh My the sound is BEAU..TI..FUL :D

Thanks - I'm hoping it does quiet down some. Can anyone estimate a percentage reduction in noise (or even just annoyance) level? 25%? 30%?

I can't describe in percetage but how I would dezcribe it, it Sooths itself out like a Melody :tup: give it about 500 miles to settle in :)

The most annoying aspect is when you're idling along (in whatever gear) and you need to speed up a little - pushing the throttle 1/4-1/2 way results in horrid resonance inside the car that gives me a headache. Is that mitigated by break-in or does it stay generally the same? If it stays about the same I think I'm going back to stock exhaust.

As for the Stillen G3 - if I go back to stock exhaust is there still a benefit to be had from keeping the G3?

Why are you convinced there is a correlation betwen the two? Keep the intake.

Figured opening exhaust and intake together were necessary to see true benefit. But if you say keeping intake still carries a benefit good. That's why I asked. Thanks...

They work better together, but they both will give you power individually.

Just out of curiosity, is your car a 7AT or a 6MT?

7at

Based on what I've read in these forums, the drone tends to be worse on 7at cars. My car is also a 7at, and if I leave it in D or DS mode, the car always shifts to the highest possible gear. This is great for fuel economy, but as you've noticed, it puts you right in the middle of the headache-inducing "drone zone."

To counter this, I've started driving in M mode all the time. By manually shifting the car, I can keep it in a lower gear to avoid the drone. In addition, the lower gear gives me better throttle response when I need to accelerate. :tup:

Take a video of your car driving away. You'll find that it sounds different and quite good. Think of all the people you drive by and will let down if you go back to stock exhaust.

Agreed - I find myself doing the same. Bummer that it negates some of the benefit of having the auto tranny.

This is another time I wish Nissan would wake up and give us a "sports" mode tranny button like the Evo has. Three or four settings for how aggressively you want (or don't want) the tranny to seek out taller gears would go a long way to being ale to stay in D but get the result we're after.

Ok 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. He 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 / frequency / 4 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, 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.

Why FI and possibly others are leaving this out? I'd guess it's the inability to determine the proper frequencies 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 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 flames 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 out 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:

1100 / 120 / 4

= 9.16667 / 4

= 2.29167 feet

(times 12 for inches)

= 27.5 inches for the length of he Helmholtz resonator tubes