Quietest Catless Header

[Oxyg3n]

What do you guys figure would be more loud? A catless el header like Tomei paired with a tame Perrin 2.5in resonated catback or an invidia n1 catback by itself w/ everything else stock?

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[HaXx]

Originally Posted by Oxyg3n

What do you guys figure would be more loud? A catless el header like Tomei paired with a tame Perrin 2.5in resonated catback or an invidia n1 catback by itself w/ everything else stock?

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i have just a N1 catback with everything else stock. i guarantee the tomei uel + catback will be louder. youre comparing a setup with one cat vs a setup with both stock cats. one cat will be louder. the N1 is often credited as the most aggressive, and while i love mine and believe its the best catback (for the dollar), single exits are heaps louder because all of the exhaust gasses only travel through a single muffler, half the sound deadening.

[JIM THEO]

The easiest the gas exit the exhaust the less the produced noise, with this in mind one of the quietest headers is the ACE!

[churchx]

HaXx: it's more dependent on actual resonators/muffler design. When i searched around, there were several single exits that were reviewed as being on quieter side. Actually CSG/Ace laguna seca one imho is the quietest from all of them including stock catback, and it features single center exit. So i highly doubt for count of exhaust tips to play any role at all for total max volume of noise.

[mav1178]

Originally Posted by HaXx

i have just a N1 catback with everything else stock. i guarantee the tomei uel + catback will be louder. youre comparing a setup with one cat vs a setup with both stock cats. one cat will be louder. the N1 is often credited as the most aggressive, and while i love mine and believe its the best catback (for the dollar), single exits are heaps louder because all of the exhaust gasses only travel through a single muffler, half the sound deadening.

Number of cats does not mean anything with regard to noise.

If I still had a BRZ I'd spend more time documenting exhaust combinations, because it's not an exact science. Everyone has their own idea of what something should sound like... but the flip side is, numbers don't lie but 90db to you is different than 90db to me.

As stated, the key question is the size of the resonators/mufflers and the internal construction.

Some header setups are actually quieter than stock in terms of maximum db, but add power to the car. A good example is this Apex'i system I documented a few years ago. It featured a factory-sized cat in the front pipe, but a massive factory-sized resonator in the factory resonator location in the front pipe as well. Most aftermarket front pipes have smaller resonators and tend to amplify exhaust noise.

Originally Posted by JIM THEO

The easiest the gas exit the exhaust the less the produced noise, with this in mind one of the quietest headers is the ACE!

This is wildly inaccurate.

[Irace86.2.0]

Originally Posted by JIM THEO

The easiest the gas exit the exhaust the less the produced noise, with this in mind one of the quietest headers is the ACE!

What you are saying is too generalized. If that was the case then no exhaust or a straight pipe would be the quietest setup, and it is very much the opposite of the quietest setup. The very way mufflers work is to disrupt air flow to remove energy and garble the sound waves with turbulence.

Originally Posted by mav1178

Number of cats does not mean anything with regard to noise. This is wildly inaccurate.

I fixed it.

[weederr33]

Originally Posted by Irace86.2.0

What you are saying is too generalized. If that was the case then no exhaust or a straight pipe would be the quietest setup, and it is very much the opposite of the quietest setup. The very way mufflers work is to disrupt air flow to remove energy and garble the sound waves with turbulence.



I fixed it.

Wrong

[Irace86.2.0]

Originally Posted by weederr33

Wrong

Which part? The part where I said mufflers remove energy and disrupt the flow, or the part where I fixed his statement because he incorrectly said that the number of cats doesn't effect the sound.

[weederr33]

Originally Posted by Irace86.2.0

Which part? The part where I said mufflers remove energy and disrupt the flow, or the part where I fixed his statement because he incorrectly said that the number of cats doesn't effect the sound.

Both

[vintagemxer]

Originally Posted by HaXx

i have just a N1 catback with everything else stock. i guarantee the tomei uel + catback will be louder. youre comparing a setup with one cat vs a setup with both stock cats. one cat will be louder. the N1 is often credited as the most aggressive, and while i love mine and believe its the best catback (for the dollar), single exits are heaps louder because all of the exhaust gasses only travel through a single muffler, half the sound deadening.

I have a single exit, dual muffler and it is really not loud, and it's tied to UEL catted headers, and a high flow catted front pipe. I'm over 60, surely not looking for a noise maker

[Irace86.2.0]

Originally Posted by weederr33

Both

[weederr33]

Originally Posted by Irace86.2.0

Ah good you get my jokes

[mav1178]

Originally Posted by Irace86.2.0

I fixed it.

Fixed what?

You can run an exhaust system with no cats and a bunch of large resonators and chambers, and it'll be just as quiet as a completely stock system.

The number of cats isn't the issue, it's the size and placement of resonators.

[Irace86.2.0]

Originally Posted by mav1178

Fixed what?

You can run an exhaust system with no cats and a bunch of large resonators and chambers, and it'll be just as quiet as a completely stock system.

The number of cats isn't the issue, it's the size and placement of resonators.

A sentence that is also a paragraph stands on its own as a statement void of qualifiers.

What you just qualified is a different statement than saying the number of cats doesn’t mean anything with regard to noise. Someone could conclude from that solo statement that a catless header could be quieter than a catted header when (for all reasonable situations) would never be the case.

You could have said, the number of catalytic converters effects the noise, but other exhaust components can do just the same without impending performance or something, and that would be fine.

I should also say, that your video doesn't corroborate your statement well. The video says the vehicle made 85lb at 10' away. That is all well and good, but that isn't the SAE standard for performing an exhaust test. The rough standard is to measure the exhaust note 20'' from the tail pipe at a 45 degree angle.

If the decibel reading at 45 degrees at 10' is 85 then we could predict what it would be at 20'' (1.67'), where I-2 is 85 dB, d-1 is 1.66'', d-2 is (10'-1.67') 8.33', and the decibel reading would be 99, which would fail in California.

http://hyperphysics.phy-astr.gsu.edu...c/isprob2.html

https://govt.westlaw.com/calregs/Doc...efault)&bhcp=1