Swapping test pipe to HFC
 

Hello everyone,

I currently have test pipe installed and it’s Danm loud. Too much for a daily. I was thinking about swapping it out to a HFC but how loud would that be? Would it be less louder and by how much?

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Less louder, if they are resonateder.

Depends on what exhaust system you’re running. If you’re running straight piped short tails, it won’t be that much quieter with cats. But if you’re running a good catback exhaust with resonators and proper mufflers, then yes it will be moderately quieter.

Moved to the correct section.

Right now, I have a resonated test pipe along with Remark version 1 axle back. I just feel like it’s gotten louder as the exhaust have broken in. Was either going to have a mini muffler welded or go for an invidia Gemini to help lower the sound.

I had the Remark V1 installed on my stock Nismo and it was obnoxiously loud. The resonance was shaking my interior apart. I removed them after an hour. Not good!

I was originally going to get the top speed axle back but they ran out of stock. Since the design looked alike I just thought it wouldn’t matter. Not sure if the top speed axle back would’ve been much different

I went from from test pipes to HFCs. I will say with my experience with different combos of exhaust, the noise level is HIGHLY dependent on your catback and how many resonators it uses. I'll list what I've run to give you and idea from Loudest to Quiet

Tomei Expreme Ti (Z33) | Invidia Test Pipes -> WAAAAY TOO LOUD
Motodyne Shockwave + Thunder Mid Pipe | Z1 HFC -> very loud, will likely run this at tracks like COTA just for fun
Tomei Expreme Ti (Z33) | Motordyne ART Pipes -> ran this for a long time, eventually was too loud for me as I couldn't hear passengers in the car and i've developed some minor hearing loss with extended use
Motordyne Shockwave + standard muffler| Invidia Test Pipes -> really good overall sound level. a tad loud but not obnoxious
Motordyne Shockwave + Standard muffler | Z1 HFC -> current setup and honestly really cleaned up the sound of the exhaust
Invidia Gemini | Invidia Test Pipes -> a really tame setup but also makes good noise when you get on it. nothing but complements with this setup.
Tomei Expreme Ti (Z33) | Stock Cats -> a bit unrefined but weight savings bro.
Invidia Gemini | ART Pipes -> honestly was a shock. very close to stock because of the hemholtz resonators. could barely hear it.
Stock

Do you think if I get the invidia Gemini and add that to my resonator test pipe that it’ll be too quiet or will the sound level would be about the same as I have now? Just need something a tad quieter

I can't tell you what it is going to be as I have never heard your setup before in person, but I do not think it's going to be loud in my opinion. This is a completely subjective topic.

I think it will be definitely quieter than what you have now. I don’t think it will be too quiet but that is very subjective. It’s hard to predict but at least you’ll have a full well-designed catback with proper x-pipe, resonators and high-flow mufflers. This should greatly “clean up” the sound.