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How to confirm stock downpipes?

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Quick question, was taking a buddy for a ride who works at a dealership. He made the comment "The last one I drove was quieter." It's been a while since he test drove one, but got me thinking, I bought my NSX used so maybe the PO installed downpipes? (Note: non-Acura dealer I purchased from said it was all stock). I don't know much about downpipes, but is there a quick way I can confirm mine are stock?
 
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aftermarket downpipes use lower cell count higher flow catalytic converters and larger diameter pipe. they flow better more for power gains and an increase in sound. typically a tune would net better gains with a downpipe but the downpipes alone will get you about 40whp. the high quality cats also do not throw a code.
 
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aftermarket downpipes use lower cell count higher flow catalytic converters and larger diameter pipe. they flow better more for power gains and an increase in sound. typically a tune would net better gains with a downpipe but the downpipes alone will get you about 40whp. the high quality cats also do not throw a code.

Thanks. Is there an easy way I can visually see if there are stock or aftermarket downpipes? (without taking a bunch parts off)
 
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not really easy to tell, SoS reuses the stock heatshields so it looks factory. some of the other brands only reuse the front heatshields. if you can see down there if the pipes are polished it's aftermarket.
 
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An interesting observation was made by one of the folks who regularly takes his 2017 to the drag strip. He noted that the downpipes reduce the exhaust backpressure which may result in a loss of torque most noticeable during drag strip runs. The reduced back pressure may in fact give you better HP at high rpms. SOS agrees. The sound quality improves dramatically. You will notice the burps and farts from the car as you slow down. I recall SOS saying that the throughput was increased over 100%. To really make a difference you would need to ram more air and fuel through the system. The JB4 manipulates some of the parameters and allows a higher level of performance with the added octane fuel. It is expensive to remove the downpipes as it requires a lot of labor.
 
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not really easy to tell, SoS reuses the stock heatshields so it looks factory. some of the other brands only reuse the front heatshields. if you can see down there if the pipes are polished it's aftermarket.

Do you know if downpipes void warranty? I'm wondering if I should just ask dealership to check the next time it goes in.
 
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depends, the dealer has to prove that the modification caused whatever failure happened. so just having downpipes the dealer cant deny warranty on your nav system. its really dealer dependent.
 
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I can only talk to Acura as far as warranty and aftermarket stuff. Acura has been pretty good about aftermarket add ones. When I had my 2001 NSX-T it was still in warranty and I had Comptech Supercharger, Headers, and an exhaust. Acura did not have a problem with any of that. With the current car, adding downpipes like those from SOS should not present problems. If you tamper with the ECU that is a no no. Otherwise most of the items will do little harm. With the JB4 depending on what you run on the settings and also the fuel you use could potentially cause problems. However as noted above, there needs to be a correlation between any engine problems and what you have done. If you read the warranty all manufactures claim breathing on the car can void your warranty. Some manufactures are harder then others. You don’t see folks putting on aftermarket stuff on Ferrari while in warranty.

Bottom line I do not believe you have an issue. My SOS downpipes were installed by an Acura Dealership during the gas tank recall.
 
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The sound quality improves dramatically. You will notice the burps and farts from the car as you slow down.

Well, that's subjective. Objectively, I guess we can say the sound CHANGES. Personally, I consider increased burps and farts to be a huge decrease in sound quality but around this forum I appear to be in the minority.
 
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Well, that's subjective. Objectively, I guess we can say the sound CHANGES. Personally, I consider increased burps and farts to be a huge decrease in sound quality but around this forum I appear to be in the minority.

Yes! Burps and Farts remind us that we have a certified race engine of excellent pedigree. Otherwise the NSXs of all versions are too quiet.
 
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