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Old 05-02-2020, 02:45 AM   #1
ItsReiko
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Will catless Front Pipe Introduce Rasp even with stock headers/overpipe?

Hi everyone, I want to add volume to my Perrin 2.5in catback and want to get a catless front pipe to do so. However, the last thing I want is any sort of rasp. I've read a lot of posts here indicating that a stock front pipe is very important to keep rasp down.

However, if I get a catless front pipe paired with my Perrin, but retain the OEM header and overpipe, I will still have any rasp issue? Would like to hear from your experiences.


Btw, what would be louder between these two? A catted aftermarket header or a catless front pipe? Considering if only one of them were changed in a setup.

Thanks
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Old 05-02-2020, 03:33 AM   #2
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there shouldn’t be any rasp, i did this with a stock header / op - invidia catless front pipe and berk muffler delete, it just gets a deeper tone and a bit loud, didn’t experience any rasp.
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Old 05-02-2020, 04:14 PM   #3
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it entirely depends on the front pipe design (and not a question of whether it has a catalytic converter or not)

I ran a Berk front pipe on a completely stock car and the stock exhaust had weird rattles under load.

Some front pipes have larger resonator or a Helmholtz resonator design that make it just as quiet as the factory front pipe without a catalytic converter.

the factory front pipe is essentially two large resonators since the catalytic converter is large with baffles. aftermarket front pipes tend to use smaller high flow universal cats, they almost always end up being the same size.
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Old 05-04-2020, 03:20 AM   #4
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Originally Posted by mav1178 View Post
it entirely depends on the front pipe design (and not a question of whether it has a catalytic converter or not)

I ran a Berk front pipe on a completely stock car and the stock exhaust had weird rattles under load.

Some front pipes have larger resonator or a Helmholtz resonator design that make it just as quiet as the factory front pipe without a catalytic converter.

the factory front pipe is essentially two large resonators since the catalytic converter is large with baffles. aftermarket front pipes tend to use smaller high flow universal cats, they almost always end up being the same size.
You seem like you might be the right person to ask: how does a stock fp with the cat punched out compare to a straight through front pipe? I'm aware the stock fp will still have the muffler in its downstream end. How much noise if any do you think that muffler in the stock fp dampens?
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Old 05-04-2020, 03:51 AM   #5
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When I changed my frontpipe with a catted/custom resonated Berk frontpipe (Tomei headers+overpipe already in the car, stock catback) the only difference was cleaner boxer sound than with the factory frontpipe and slightly louder.
So it really depends from the frontpipe resonators, buy one that has at least two of them say Apexi, HKS etc, I sell mine almost new but you are faraway!

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Old 05-04-2020, 05:46 PM   #6
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You seem like you might be the right person to ask: how does a stock fp with the cat punched out compare to a straight through front pipe? I'm aware the stock fp will still have the muffler in its downstream end. How much noise if any do you think that muffler in the stock fp dampens?
all depends on the size of your resonators throughout the exhaust system.

there's no way to give you an answer, because volume of sound (in db) is one of the worst things to quantify with words.

It just comes down to what the end goal is: to say "I want something louder and more aggressive but no rasp or annoying things" is very generic. to have something else to compare against is better... but YouTube videos filmed on a GoPro or cell phone doesn't help because of the poor microphone used to capture sound.
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Old 05-04-2020, 06:24 PM   #7
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I have to add note, size not as in "bigger is better", but as in "right" size. Depending on their size resonators work for specific frequencies. If they are to reduce drone/rasp at specific frequencies they need to be sized right for that. It's simpler to design/test exhaust system as a whole (or to work with something most common, eg. stock rest of exhaust bits), but when customers do different combinations of parts from multiple vendors, result is often left to chance/luck. :/
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Old 05-04-2020, 07:23 PM   #8
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Originally Posted by ItsReiko View Post
Hi everyone, I want to add volume to my Perrin 2.5in catback and want to get a catless front pipe to do so. However, the last thing I want is any sort of rasp. I've read a lot of posts here indicating that a stock front pipe is very important to keep rasp down.

However, if I get a catless front pipe paired with my Perrin, but retain the OEM header and overpipe, I will still have any rasp issue? Would like to hear from your experiences.


Btw, what would be louder between these two? A catted aftermarket header or a catless front pipe? Considering if only one of them were changed in a setup.

Thanks
I have HKS dual resonator front pipe with HKS HiPower SpecL exhaust and stock header - not much louder and no rasp or drone.
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Old 05-05-2020, 12:40 PM   #9
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I would like to know how the Fujitsubo dual resonated cattless front pipe would compare to a Resonated and Catted (like the JDL Ultra Quiet) front pipe, in terms of sound level and rasp.

Perhaps @mav1178 can speak to this?

This would be in conjunction with a 4-2-1 EL header and a MXP SP cat back. I want to know if I should expect a huge jump in noise by replacing the stock front pipe with either of those options.
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Old 05-05-2020, 01:22 PM   #10
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I will add my experience, I went with jdl catless header with stock FP and invidious Q300 catback. Very quiet at idle but good sound when on it. Went to the hooker FP catted with helmholz resonator and was only slightly louder than stock. The cat broke loose so I went with jdl catted and resonated FP. Maybe a little louder than the hooker. I am getting more rasp but I think my Q300 is getting louder over time (known issue). Debating what to do about it. Sounds great in the car, but sometimes a little raspier than it used to be with the windows open. Only thing stopping me is it’s so expensive to change for a sound that may not be that different.
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Old 05-05-2020, 02:02 PM   #11
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I will add my experience, I went with jdl catless header with stock FP and invidious Q300 catback. Very quiet at idle but good sound when on it. Went to the hooker FP catted with helmholz resonator and was only slightly louder than stock. The cat broke loose so I went with jdl catted and resonated FP. Maybe a little louder than the hooker. I am getting more rasp but I think my Q300 is getting louder over time (known issue). Debating what to do about it. Sounds great in the car, but sometimes a little raspier than it used to be with the windows open. Only thing stopping me is itís so expensive to change for a sound that may not be that different.
The cat broke loose in my Hooker FP as well.
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Old 05-05-2020, 05:39 PM   #12
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Originally Posted by RayRay88 View Post
I would like to know how the Fujitsubo dual resonated cattless front pipe would compare to a Resonated and Catted (like the JDL Ultra Quiet) front pipe, in terms of sound level and rasp.

Perhaps @mav1178 can speak to this?

This would be in conjunction with a 4-2-1 EL header and a MXP SP cat back. I want to know if I should expect a huge jump in noise by replacing the stock front pipe with either of those options.
The Fujitsubo is absolutely the quietest and less raspy, but it's uncatted. I'll go with a catless header and I want to keep a cat.
There's a catted version of Fujitsubo front pipe, but it's sold just with all the EPU exhaust.
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Old 05-05-2020, 10:07 PM   #13
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The cat broke loose in my Hooker FP as well.
Yeah, mine sat in the shed for a longtime. Just sold it to a local guy. He got a deal, says heís gonna have his guy weld it in. Iíll check back with him in a month or so and see how it turn out. Itís a nice piece but the quality just is not that good.
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Old 05-05-2020, 10:55 PM   #14
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I will add my experience, I went with jdl catless header with stock FP and invidious Q300 catback. Very quiet at idle but good sound when on it. Went to the hooker FP catted with helmholz resonator and was only slightly louder than stock. The cat broke loose so I went with jdl catted and resonated FP. Maybe a little louder than the hooker. I am getting more rasp but I think my Q300 is getting louder over time (known issue). Debating what to do about it. Sounds great in the car, but sometimes a little raspier than it used to be with the windows open. Only thing stopping me is it’s so expensive to change for a sound that may not be that different.
Which component of your exhaust is causing your rasp?

In the end, I went with a catless Tomei EL header to pair with my stock over/front pipe and Perrin 2.5 resonated catback. From the single youtube video on earth that you can find with this setup, it sounds like it will increase volume but still have zero rasp, which I did not previously know was possible with a catless header.

I'm in this mostly for sound, but hopefully this will also increase performance a bit since I'm already running e85 on stock 2017 headers.
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