JHM B8 High-Flow Cat Downpipes with X-Pipe

[MSq5]

Loud!

Loud +2.

I guess it depends on preference. Exhaust sound preference is very subjective. I hate to say this, but to my ear it sounds like some of the loud, raspy aftermarket exhausts on Japanese cars like the Nissan Z. Six cylinder engines are difficult to design exhaust systems for because they are naturally guttural and raspy due to the nature of the exhaust impulses.

I do not criticize. If that is what he likes, then it’s right for him. Probably for many others. It’s all good.

I’m looking for something more “refined”. That will be difficult with gutted or downstream cats or going catless, I realize. This is where carefully placed straight-through resos are likely to smooth things out without loss of power. That has been my experience with other cars when running high flow catless exhausts. The challenge will be finding room for them. I want quiet but mellow, just a little more growl at full throttle, with no loss of power. Maybe I’m asking too much.

[5chnell]

Not a great one but here’s the following:

https://youtu.be/-gft26hb0Ko

JHM V2 Test Pipes (wrapped)
JHM DPs (Integrated baffles)
AWE track catback section w/ touring mufflers

[bluestyle55]

Not a great one but here’s the following:

https://youtu.be/-gft26hb0Ko

JHM V2 Test Pipes (wrapped)
JHM DPs (Integrated baffles)
AWE track catback section w/ touring mufflers

Good clip 5chnell. Almost sounds a bit more linear than without the baffle. Would you mind doing the same clip but from inside the car with windows up and windows down.

[5chnell]

Good clip 5chnell. Almost sounds a bit more linear than without the baffle. Would you mind doing the same clip but from inside the car with windows up and windows down.

I'll have something up tonight along with a fairly thorough review on their integrated baffled X-pipe/downpipes along with V2 test pipes.

[datdonk_mkv]

I'll have something up tonight along with a fairly thorough review on their integrated baffled X-pipe/downpipes along with V2 test pipes.

Did you put anything up? Not sure if you were gonna post it here, YouTube or start another thread. I'm curious to hear it

[BDP]

Man I really need to get around to installing mine, it's just too cold here right now for me to be out in the garage messing around. Plus, I've been shopping RS3's and if I can find a local buyer for my S4 I'll package these in and let them install it...lol.

[Jake@JHM]

Yea with only the race pipes just about every exhaust system is going to be loud. The DPs with HFC help and then the Baffle system on top of that helps further.

[sikbuck]

Yea with only the race pipes just about every exhaust system is going to be loud. The DPs with HFC help and then the Baffle system on top of that helps further.

When will you have the non-x DP with HFC and baffle in stock?

[Jake@JHM]

When will you have the non-x DP with HFC and baffle in stock?

They are made to order right now until we are caught up. Then we will have stock of them. If you ordered today it should ship within a week or two.

[Fizzy]

Nothing is cleaner than the awe touring alone you gotta love that smoothness i just put the jhm’s because im going stage 2 ie crackle tune


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[Jake@JHM]

From another thread:

Test pipes & downpipes installed. What a beoch to install. Thankfully we were using my buddy's shop and his lift - without access to his extensive repertoire of tools and the lift making our lives 10x easier, I'm not sure we could have gotten the job done.

We ended up using the ol' sawzall to cut the cats up to get to the top 2 bolts on the passenger side, and to get the cat out on the driver side. We didn't have to remove the x-brace, only the heat shielding from the wheel wells to get a better view.

I'm impressed with how little drone there is for a fully "test piped" car. The volume is similar to my non-res DP's with the stock cats & AWE Touring, but with less drone at highway speeds. Definitely raspier (to be expected with test pipes) but overall really happy.

Sound clips coming, and IE second pulley & new fuel pump are in the mail. Waiting on IE to finish the throttle body adapter for the SQ intake and then I'll get the throttle body ordered as well!

[dp.s4]

Any sound clips out there of the new catted DPs with the silencers in the test pipes? I have not been able to find any yet. I will take anything over nothing, but would prefer the cat back to be a AWE Touring.

[Jake@JHM]

Any sound clips out there of the new catted DPs with the silencers in the test pipes? I have not been able to find any yet. I will take anything over nothing, but would prefer the cat back to be a AWE Touring.

An SQ5 Customer (eruben123 quoted above) is making a video on them for his youtube: Ignitiontube

Then our customer 5chnell is also making a video on them.

Both have AWE Touring catbacks

[Jake@JHM]

Teaser for the boys

Here is a teaser.

JHM Race Pipes: https://jhmotorsports.com/exhaust-ra...7-a7-3-0t.html

JHM HFC Downpipes w/IBS: https://jhmotorsports.com/exhaust-hi...-4-2l-fsi.html

AWE Touring: https://jhmotorsports.com/catalogsea...?q=AWE+Touring

[scls4]

Here is a teaser.

JHM Race Pipes: https://jhmotorsports.com/exhaust-ra...7-a7-3-0t.html

JHM HFC Downpipes w/IBS: https://jhmotorsports.com/exhaust-hi...-4-2l-fsi.html

AWE Touring: https://jhmotorsports.com/catalogsea...?q=AWE+Touring

Actually that sounds pretty damn good launching. Close to AWE touring sound with cats.

[Jake@JHM]

Actually that sounds pretty damn good launching. Close to AWE touring sound with cats.

Yea it is actually quieter than his previous setup that was AWE Touring -> IE Downpipes -> Stock Cats

[datdonk_mkv]

Yea it is actually quieter than his previous setup that was AWE Touring -> IE Downpipes -> Stock Cats

We must not be listening to the same video because that is most definitely NOT quieter by any means. Listening to this video and his previous video side-by-side when he installed the non-res IE DP's there is a clear increase in volume (as expected, with test pipes).

I understand exhaust tone is subjective to everyone's different opinions, but my hope with this setup was that it would be quiet enough for my taste so I could pull the trigger. I will wait for his full review video on the setup before I make a definitive answer, but just from this short clip those baffles don't do enough for me.

I am curious though, if he had gotten the x-pipe version of the DP's, what the tone would have sounded like.

[MSq5]

We must not be listening to the same video because that is most definitely NOT quieter by any means. Listening to this video and his previous video side-by-side when he installed the non-res IE DP's there is a clear increase in volume (as expected, with test pipes).

I understand exhaust tone is subjective to everyone's different opinions, but my hope with this setup was that it would be quiet enough for my taste so I could pull the trigger. I will wait for his full review video on the setup before I make a definitive answer, but just from this short clip those baffles don't do enough for me.

I am curious though, if he had gotten the x-pipe version of the DP's, what the tone would have sounded like.

Microphone placement affects volume, as does sensitivity. Hard to make valid comparisons. I’m no exhaust tuning guru, but my experience in running catless on several other platforms found that one or two strategically placed resonated x-pipes or free standing resos often works miracles. We are likely to need to keep experimenting on reso design and location to find the right combo.

The most effective I’ve found are the straight-through Vibrant UltraQuiet resos, but they don’t make a dual in and out design and their singles may be too large to fit. Damn effective, though, in outright killing drone and rasp without loss of power.

[Jake@JHM]

We must not be listening to the same video because that is most definitely NOT quieter by any means. Listening to this video and his previous video side-by-side when he installed the non-res IE DP's there is a clear increase in volume (as expected, with test pipes).

I understand exhaust tone is subjective to everyone's different opinions, but my hope with this setup was that it would be quiet enough for my taste so I could pull the trigger. I will wait for his full review video on the setup before I make a definitive answer, but just from this short clip those baffles don't do enough for me.

I am curious though, if he had gotten the x-pipe version of the DP's, what the tone would have sounded like.

Just going off what he told me though I believe he was referring to driving/cruising around town. WOT should be louder but not by much. I haven't heard this car in person.

[harrisonk8]

Can these be a direct OEM replacement with no tune ? Just looking for different options other than Magnaflow or OEM.

[Jake@JHM]

Can these be a direct OEM replacement with no tune ? Just looking for different options other than Magnaflow or OEM.

They are not an OEM Replacement, as they cats are high flow, and they are relocated downstream. However with the race pipes and the j-bung o2 sensor spacers we sell you can run this without a CEL.

[Shuga]

They are not an OEM Replacement, as they cats are high flow, and they are relocated downstream. However with the race pipes and the j-bung o2 sensor spacers we sell you can run this without a CEL.

Would it pass emissions though?


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[Jake@JHM]

Would it pass emissions though?


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Some states and counties yes. They aren't 50 state legal though.

[Shuga]

Some states and counties yes. They aren't 50 state legal though.

I’m in NY.


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[harrisonk8]

Thanks, Jake. If I purchase with the j-bung, can I run it safely on a stock tune? I am asking because I know some other FI cars that get into issues running HFC on factory tune. Thanks again for your response.

[Jake@JHM]

Thanks, Jake. If I purchase with the j-bung, can I run it safely on a stock tune? I am asking because I know some other FI cars that get into issues running HFC on factory tune. Thanks again for your response.

I'm running this on stock software with j-bung we offer. Using the biggest hole insert and NO CEL

https://jhmotorsports.com/j-style-ox...ess-steel.html

[emilio10]

So really condiering these JHM HFC + baffled downpipes to combine with my JHM test pipes + ECS resonated valved cat back..
But just to be sure, should I get the 2.5" downpipe option to attach to the ecs exhaust? Here's a picture for reference of how the ecs exhaust "center section" attaches to the ecs downpipes+xpipe section so not totally sure if the 2.5" JHM downpipes would slide into the "center section" but it should right?

ATTACH]162342[/ATTACH]


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[Jake@JHM]

So really condiering these JHM HFC + baffled downpipes to combine with my JHM test pipes + ECS resonated valved cat back..
But just to be sure, should I get the 2.5" downpipe option to attach to the ecs exhaust? Here's a picture for reference of how the ecs exhaust "center section" attaches to the ecs downpipes+xpipe section so not totally sure if the 2.5" JHM downpipes would slide into the "center section" but it should right?

ATTACH]162342[/ATTACH]


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If that center section is swedged open to accept 2.5" there is a good chance it will just bolt right up. Go with standard downpipe and not the X so you have room to move the individual pipes around in case they are not in stock location.

Worse case any muffler shop can whip up an adapter for cheap.

[emilio10]

If that center section is swedged open to accept 2.5" there is a good chance it will just bolt right up. Go with standard downpipe and not the X so you have room to move the individual pipes around in case they are not in stock location.

Worse case any muffler shop can whip up an adapter for cheap.

Thank you! Just ordered the non x pipe version. So excited for these!


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[Jake@JHM]

Thank you! Just ordered the non x pipe version. So excited for these!


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Thanks for the order!

[timmyzr1]

So really condiering these JHM HFC + baffled downpipes to combine with my JHM test pipes + ECS resonated valved cat back..
But just to be sure, should I get the 2.5" downpipe option to attach to the ecs exhaust? Here's a picture for reference of how the ecs exhaust "center section" attaches to the ecs downpipes+xpipe section so not totally sure if the 2.5" JHM downpipes would slide into the "center section" but it should right?

ATTACH]162342[/ATTACH]


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How is this set up turned out??

[emilio10]

How is this set up turned out??

Overall I'm pretty happy with it! Still need to get sound clips although there does seems to be a tiny leak where the jhm downpipes join the ecs exhaust. Also sounds a tiny bit rattle-y from 1800-2400ish rpm but I can never seem to get rid of thag even after heat wrapping the downpipes and adding mopar dampers. But besides that it's a lot more quiet now especially at highway speeds, I can't even hear the exhaust and pretty much no drone. With valves open I can't hear it as much in the cabin at all anymore after 4k rpm, only the SC whine, and the overall volume has gone down quite a bit. Really digging this setup since I'm over loud cats now after having only test pipes and non resonated downpipes lol


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[datdonk_mkv]

Overall I'm pretty happy with it! Still need to get sound clips although there does seems to be a tiny leak where the jhm downpipes join the ecs exhaust. Also sounds a tiny bit rattle-y from 1800-2400ish rpm but I can never seem to get rid of thag even after heat wrapping the downpipes and adding mopar dampers. But besides that it's a lot more quiet now especially at highway speeds, I can't even hear the exhaust and pretty much no drone. With valves open I can't hear it as much in the cabin at all anymore after 4k rpm, only the SC whine, and the overall volume has gone down quite a bit. Really digging this setup since I'm over loud cats now after having only test pipes and non resonated downpipes lol


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I'm very interested in hearing this setup. Video clips would be lovely! I'm waiting to hear someone else's setup that actually has a decent tone before I pull the trigger on a setup for my own car.

[wrxkyle]

question, these look like a massive restriction in the exhaust. has anyone flow tested these? and can anyone comment as to the 2k-3k resonance (trombone sound) experienced on many test piped s4's? do these eliminate that or just help with idle volume and some rasp?

has anyone done any performance checks before and after?

[emilio10]

Has anyone had to cut off a bit of length on their JHM baffled/HFC (non xpipe) downpipes to make them fit? I've been trying to install them to mate up with my ECS valved exhaust but I can't get these JHM pipes on to save my life, they're too long and won't go into the ecs exhaust properly because of the excessive length


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[Jake@JHM]

Has anyone had to cut off a bit of length on their JHM baffled/HFC (non xpipe) downpipes to make them fit? I've been trying to install them to mate up with my ECS valved exhaust but I can't get these JHM pipes on to save my life, they're too long and won't go into the ecs exhaust properly because of the excessive length


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Is it necked down to stock, or full 2.5"?

Neck down to stock is also in stock location, so any exhaust that mates to stock downpipes will work. With 2.5", everyone does it differently so depending on the system you may need to trim or add a small amount.

[emilio10]

Is it necked down to stock, or full 2.5"?

Neck down to stock is also in stock location, so any exhaust that mates to stock downpipes will work. With 2.5", everyone does it differently so depending on the system you may need to trim or add a small amount.

The ecs valved exhaust is a full 2.5" exhaust so that's the option I picked for the JHM downpipes. Just got it fitted on though with a bit of modification at a muffler shop! Seems like it was more of a pain than for others because I have an S5 and not an S4 making this exhaust lengths a bit different. IMG_4411.jpg


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[BLKPERL]

What is the difference between the X-Pipe and non X-Pipe versions?

[Jake@JHM]

What is the difference between the X-Pipe and non X-Pipe versions?

One set has an X-Pipe and the other is a tradition downpipe with no X-Pipe

Non-x



X-pipe

[4Ringsof4ury]

Double x pipes have been becoming a bigger thing in the past few years in the American V8 community. They've found that it helps with drone and in some cases even helps with maintaining torque without sacrificing horsepower.