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So I was reading a bit about J Pipes. The concept seems pretty slick. It's basically a pipe that is T-ed into the existing exhaust and capped at the end which acts as a resonator for drone.
This is exactly what the Infiniti Motorsports Helmholtz exhaust design does. Many exhaust designs have taken the Helmholtz resonance idea and added a resonator on the J-pipe to provide the best solution to reducing drone. The key, as you mentioned, is the length of the neck: Helmholtz resonance - Wikipedia. I would highly recommend adding a resonator on the J-pipe to improve results and reduce the required length of the neck.

With my current setup, I have two resonators on the mid-pipe (aFe Power Y-pipe and mid-pipe) and two Helmholtz resonators on the axle-back (Infiniti Motorsports center-exit kit). Overall, I quite love the sound of my setup, but I look forward to upgrading the turbos and hopefully improving the noise by replacing the restrictive OEM turbos.
 

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5oh_mo said:

" I really think the Vibrant Quiet in its current place of your aero mufflers would have been more effective. Instead of having 4 mufflers in your setup and adding another componenet to fail down the road."

This sure seems to indicate that....the Vibrant Quiet is a resonator. My post about mufflers vs. resonators was directed to 5oh_mo.
I took it to mean that he was interchanging the terms mufflers and resonators to mean the same thing. So the 4 is the one Aero resonator I just installed, the next future one downstream, if I do so, and the two existing Stillen mufflers. I think he was saying that if I just bought his suggested Vibrant Quiet, I would only need one in the midpipe and not possibly two. I don't think he was suggesting to change out the Stillen mufflers.

Anyway, enough of that, lol
 

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2:35am, time for bed. Night guys! :)
 

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How would the HKS Resonated LDPs do on a stock '18 Luxe 3.0t AWD with just a JB4 and 91 octane? Any idea if I'd see gains? Would there be any CELs or anything?
 

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I would say that you would definitely feel an increase in power. No CELs. The full benefit of the LDPs would shine with a better CBE though.
 
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I would say that you would definitely feel an increase in power. No CELs. The full benefit of the LDPs would shine with a better CBE though.
Thanks. From what I've read it appears this can be done piecemeal (add LDPs then the CBE later). Any idea if this is in fact the case?
 

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You definitely can do it that way. I did CBE and then LDP. I wanted to see the incremental differences. But it would probably be cheaper to do at once.
I went with the JB4 first and experienced a tremendous increase in power. I drove with that for about a year then added the FI CBE. I felt more power over the stock CBE. I drove with that for several months and then added the HKS LDPs. Those provided even more power, especially at the low end.

It would be cheaper to do both at the same time if you're not doing the installation yourself. If you are doing the installation, then it would be easier to do them at the same time.
 
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Thanks for the replies. I've had the jb4 for a couple months or so and love it (even tho I'm sorta limited to map 1 with 91). I'm leaning towards the FI CBE & HKS LDPs both resonated. Need to be sure I'll pass emissions (Arizona) and see if Stealership will put up a fuss or not regarding my extended warranty.
 

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Thanks for the replies. I've had the jb4 for a couple months or so and love it (even tho I'm sorta limited to map 1 with 91). I'm leaning towards the FI CBE & HKS LDPs both resonated. Need to be sure I'll pass emissions (Arizona) and see if Stealership will put up a fuss or not regarding my extended warranty.
The local dealership I use (GM) would not swap LDPs because of the regulations regarding the removal of a pollution control device. Those regs were written before secondary cats and their specific function (for cold startup) started showing up on more recent cars. Fortunately, I don't live in an area that requires emissions testing but I would be very interested to see how the car fares without secondary cats.

I had no problem finding a muffler shop that would swap LDPs. They don't give a sh1t.
 

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How would the HKS Resonated LDPs do on a stock '18 Luxe 3.0t AWD with just a JB4 and 91 octane? Any idea if I'd see gains? Would there be any CELs or anything?
If you are convinced you'll only be doing LDPs and not a full CB later, then you don't need resonated LDPs and you can save money by going with Megan Racing LDPs. If you think you'll be adding a full CB later, and you want your system as quiet as you can get it, yes, get the resonated LDPs. You'll still see modest gains with only catless LDPs (but not as much as a full UDP-Back system). No CELs.


Thanks. From what I've read it appears this can be done piecemeal (add LDPs then the CBE later). Any idea if this is in fact the case?
You can install LDPs and a CB in any order but I do recommend you don't piece a CB (Y-pipe from here, mid-pipe from there, axle back from here...). Buy a complete CB from a manufacturer who designed it to work together. Look for resonators and decent sized mufflers if sound is a concern.

Good luck.
 

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Just want to let you guys know I installed the HKS Resonated Lower Downpipes about two weeks ago. It has been above 95⁰F every single day here in South Florida, and even with the extreme heat I can feel the power increase. Definitely more torque, I can slide easier if I want to.

I only have intakes, and LDP. Everything else is stock. Hopefully will add a FI catback in the future and a Heat exchanger before tuning.
 
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Just want to let you guys know I installed the HKS Resonated Lower Downpipes about two weeks ago. It has been above 95⁰F every single day here in South Florida, and even with the extreme heat I can feel the power increase. Definitely more torque, I can slide easier if I want to.

I only have intakes, and LDP. Everything else is stock. Hopefully will add a FI catback in the future and a Heat exchanger before tuning.
You will not be disappointed with the FI CBE. Pricey but very high quality product. I have the 10" sport mufflers with non-res x-pipe and it is loud, but awesome. I dont know what sound you are looking for, but Avedis53 swears by the 14" touring mufflers with resonated x-pipe if you want a reserved sound until you hit it (also absolutely zero drone with this option). My set up is loud on start up and acceleration, but quiets down once warmed up. Since it is non-resonated there is the slightest drone only when on the highway running above 2800rpms (basically when you are cruising @78mph and accelerate above 80). Also the downshifts in sport mode sound amazing.
 

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Did the driver side hks ldp this morning, took me 4-5hrs on one side lol and im exhausted as hell, the most difficult part for me was swapping o2 sensor , and since hks doesnt use studs thats connects to upper dp , just traditional nut & bolt, so finding ways to tighten both end was very challenging by myself, imma rest for a full week before doing passenger side. happy july4th everyone dont get too drunk:sleep:
 

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Did the driver side hks ldp this morning, took me 4-5hrs on one side lol and im exhausted as hell, the most difficult part for me was swapping o2 sensor...
The right side rear O2 sensor is just as much fun.
 

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Validates my repeatedly saying the secondary cats are the biggest choke point in the OEM exhaust system.

I went with resonated X-pipe and 14" mufflers and glad I did. (FI)
 

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Did the driver side hks ldp this morning, took me 4-5hrs on one side lol and im exhausted as hell, the most difficult part for me was swapping o2 sensor , and since hks doesnt use studs thats connects to upper dp , just traditional nut & bolt, so finding ways to tighten both end was very challenging by myself, imma rest for a full week before doing passenger side. happy july4th everyone dont get too drunk:sleep:
I posted this tip about using a little spray glue on the washer and lock washer to keep them upside-down on the stud by themselves. Life saver.

 
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Did the driver side hks ldp this morning, took me 4-5hrs on one side lol and im exhausted as hell, the most difficult part for me was swapping o2 sensor , and since hks doesnt use studs thats connects to upper dp , just traditional nut & bolt, so finding ways to tighten both end was very challenging by myself, imma rest for a full week before doing passenger side. happy july4th everyone dont get too drunk:sleep:
I'm already planning to take a day off when my HKS LDP arrives - most likely on Friday-Sat. My passenger side O2 sensor should be easy as the dealer recently replaced it. The DS might be give me a little pain though. I still have time lose some belly fat to make sure I'll fit in under the car.
 
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