[cmitchell17]

Originally Posted by bowtie_thunder

If I remember correctly, yes, swapping the factory X-pipe with an H-Pipe does replace the raspiness with deep tone (like how the Mustangs do) and takes the noise down a decibel or two in the cabin.

The problem is that it doesn't quiet it nearly as much as the X, and in some cases, I've seen instances where it actually increases drone.

Its so weird to me to think that just going from a h to an x pipe makes a difference. So I'm kind of confused you are saying only in some cases a H pipe can increase drone when added?

My plan would be to add an H pipe to the stock NPP but add it up near the front before the secondary cats. What I have heard is supposedly the issue is that the H pipe allows excess pressure spikes, that supposedly cause the raspy poppy noise, to balance out between the 2 banks.

The first thing I think I need to figure out is ensure that the noise I hate is what everyone else is describing as rasp. To me its the most annoying, unrefined, poppy, ricery, fartty poppy, fart can exhaust noise. You hear it on ever single muffler deleted/straight piped lifted truck around here too.

[bowtie_thunder]

Originally Posted by cmitchell17

Its so weird to me to think that just going from a h to an x pipe makes a difference. So I'm kind of confused you are saying only in some cases a H pipe can increase drone when added?

My plan would be to add an H pipe to the stock NPP but add it up near the front before the secondary cats. What I have heard is supposedly the issue is that the H pipe allows excess pressure spikes, that supposedly cause the raspy poppy noise, to balance out between the 2 banks.

The first thing I think I need to figure out is ensure that the noise I hate is what everyone else is describing as rasp. To me its the most annoying, unrefined, poppy, ricery, fartty poppy, fart can exhaust noise. You hear it on ever single muffler deleted/straight piped lifted truck around here too.

Yes, both help to regulate exhaust to help scavenge the gases from the cylinders and create better flow. However, one is simply better than the other in areas.

X-Pipes are good at exhaust gas scavenging by forcing the exhaust from each cylinder to converge to a point and speed up flow. And while it reduces cabin noise, it also increases high-pitched sounds. H-Pipes are good for equalizing the exhaust pulses, but aren't very good at scavenging.

What I was referring to earlier was with a friend's build. He replaced his X with a H-pipe in his sixth-gen that had a Stainless Works catback system, and it added some noticeable drone. However, I believe that had more to do with the diameter of his pipes more than anything.

"Rasp" refers to the annoying high-pitched screaming that comes from the exotics and supercars that cause crackles, pops, burbling etc. So yes, you've got that right.

From a personal standpoint, I honestly could not stand the stock exhaust for that crazy-sounding stuff, which is why I went with MBRP. I initially planned on replacing the factory X with a resonated one, but since the axlebacks I have already come with helmholtz ressies, I decided to leave it be.

[cmitchell17]

Originally Posted by bowtie_thunder

Yes, both help to regulate exhaust to help scavenge the gases from the cylinders and create better flow. However, one is simply better than the other in areas.

X-Pipes are good at exhaust gas scavenging by forcing the exhaust from each cylinder to converge to a point and speed up flow. And while it reduces cabin noise, it also increases high-pitched sounds. H-Pipes are good for equalizing the exhaust pulses, but aren't very good at scavenging.

What I was referring to earlier was with a friend's build. He replaced his X with a H-pipe in his sixth-gen that had a Stainless Works catback system, and it added some noticeable drone. However, I believe that had more to do with the diameter of his pipes more than anything.

"Rasp" refers to the annoying high-pitched screaming that comes from the exotics and supercars that cause crackles, pops, burbling etc. So yes, you've got that right.

From a personal standpoint, I honestly could not stand the stock exhaust for that crazy-sounding stuff, which is why I went with MBRP. I initially planned on replacing the factory X with a resonated one, but since the axlebacks I have already come with helmholtz ressies, I decided to leave it be.

What do you think about putting a H pipe up say maybe right after the primary cats? Someone did this on the CTSV forums and it supposedly cut out all the rasp? I guess I would still leave the rest of the stock exhaust intact behind it so I would leave the X pipe and have a H and and X pipe.

Might be a dumb idea but to just test the concept somewhat I was trying to find some small diameter pipe or maybe silicone tubing and connect that to the #2 O2 sensor from bank to bank? You think that would do anything? I think the O2 sensor threads are M18, I was trying to find a M18 barb fitting and get some silicone tubing to connect?

They claimed this worked by "balancing high pressure spikes" what do you think?

[oldman]

you could try 3/4 copper water pipe, don't think it will do much, I personally highly question that a H pipe can remove all rasp.

[cmitchell17]

Originally Posted by oldman

you could try 3/4 copper water pipe, don't think it will do much, I personally highly question that a H pipe can remove all rasp.

I am very skeptical as well. Biggest reason is that if the design team could have removed it easily and cheaply enough, I think they would have. It seems like they knew the cats would attenuate the sound enough it wouldn't matter. I wonder if I could take the stock downpipes back off and put something in where the cats were to attenuate the sound? I feel like packing wouldn't make a difference.

[chaospiece]

My mustang has a custom built exhaust. First and h-pipe killed alot of the signature coyote rasp sound.
Then the shop measured the way the pipes shake and added 2 resonators midway to the exhaust and h-pipe.
Sounds like an old school V8 like the amg 6.3.

The thing Is, the mustang has the cross over right after the cats when the pipes converge.
The Camaro has the cross over at the end of the exhaust system so all that vibrating straight pipe is ocilating the rasp.
I dont know why Chevy did that, maybe packaging purposes?

My best bet is for resonators where the secondary cats are, and an h where the factory x is.
I kinda got used to having these 2 cars sounding different, I have an h pipe laying around but idk if I want to take away the camaros Nascar sound at higher revs.

[avalonandl]

Originally Posted by chaospiece

My mustang has a custom built exhaust. First and h-pipe killed alot of the signature coyote rasp sound.
Then the shop measured the way the pipes shake and added 2 resonators midway to the exhaust and h-pipe.
Sounds like an old school V8 like the amg 6.3.

The thing Is, the mustang has the cross over right after the cats when the pipes converge.
The Camaro has the cross over at the end of the exhaust system so all that vibrating straight pipe is ocilating the rasp.
I dont know why Chevy did that, maybe packaging purposes?

My best bet is for resonators where the secondary cats are, and an h where the factory x is.
I kinda got used to having these 2 cars sounding different, I have an h pipe laying around but idk if I want to take away the camaros Nascar sound at higher revs.

I agree, they should have put the X-pipe after the cats....

[oldman]

Originally Posted by cmitchell17

I am very skeptical as well. Biggest reason is that if the design team could have removed it easily and cheaply enough, I think they would have. It seems like they knew the cats would attenuate the sound enough it wouldn't matter. I wonder if I could take the stock downpipes back off and put something in where the cats were to attenuate the sound? I feel like packing wouldn't make a difference.

Hi-flow cats are a good resonator..

[keep_hope_alive]

TTT for all of the new Camaro owners.

Any updated information or is the 2023 NPP the same? I think this is awesome.

[cmitchell17]

I don't know this 100% sure but pretty sure everything is exactly the same including the NPP and muffler.

I added the magnaflow oval muffler with the built in x pipe with perforations and packing. I welded the maganflow in place of the factory "x" pipe. It does attenuate the loud spikes very well so no more obnoxious kid like startup and WOT with the NPP valves open. However, it attenuates all the time at all the frequencies, which means idle too. So now it kind of sounds like a old POS car with a rusty muffler at idle or like you backed your tailpipe end into the water and it bubbling and muffled. I think the tradeoff for getting rid of the obnoxiousness was probably worth it. I need to listen to it from the outside when someone else is driving it to really be able to tell how it sounds.

[2SS Capt]

Originally Posted by keep_hope_alive

TTT for all of the new Camaro owners.

Any updated information or is the 2023 NPP the same? I think this is awesome.

NPP hasn't changed...