X-pipe or H-pipe - Pontiac G8 Forum: G8 Forums - G8Board.com
Exhaust Tech Headers, Catbacks, Mufflers, lack of mufflers

View Poll Results: Which one
X-pipe only 34 85.00%
H-pipe only 4 10.00%
X and H pipe 2 5.00%
None, leave it stock 0 0%
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post #1 of 25 (permalink) Old 09-17-2009, 09:30 PM Thread Starter
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X-pipe power gains

What are the HP/TQ gains of adding an x-pipe? Also, how does the sound change from stock by just adding an x-pipe? What size did you guys use?

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post #2 of 25 (permalink) Old 09-17-2009, 09:42 PM
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i used a magnaflow xpipe worked great.. i would say 1-5hp to be honest...

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post #3 of 25 (permalink) Old 09-17-2009, 09:53 PM
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Quote:
Originally Posted by shane View Post
i used a magnaflow xpipe worked great.. i would say 1-5hp to be honest...
Hey Shane, which one did you use. I'm not sure which one for the stock piping to get from Maryland speed. Thanks

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post #4 of 25 (permalink) Old 09-17-2009, 09:55 PM
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Stock should be the 2.25" pipe. Plan to get me the Magnaflow from summit racing
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post #5 of 25 (permalink) Old 09-17-2009, 09:55 PM
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Originally Posted by BluYa76 View Post
Hey Shane, which one did you use. I'm not sure which one for the stock piping to get from Maryland speed. Thanks

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post #6 of 25 (permalink) Old 09-17-2009, 09:56 PM
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https://www.g8board.com/forums/showth...highlight=pipe

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post #7 of 25 (permalink) Old 09-18-2009, 08:25 AM
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Very minimal change on sound and power. Barely noticable if noticable at all but better than doing nothing. I think it is best as part of an aftermarket muffler swap and/or header install.

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post #8 of 25 (permalink) Old 09-19-2009, 01:20 PM
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I just got one installed by a local shop on thursday and they did a great job. The sound did not change at all and the power is not that significant. It is however a good place to start if your going the route of a custom exhaust rather than buying a catback. When I was looking at the main resonator telling the guy at the shop what I wanted I did notice what looks like 2 more resonators (one one each side) just a little after the large one in the center. Maybe if you had them replace those too you would get better sound from the stock mufflers. I am going to try that next.
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post #9 of 25 (permalink) Old 09-19-2009, 01:33 PM
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Im thinking of adding an h pipe monday and getting ride of all the gunk in the middle
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post #10 of 25 (permalink) Old 12-11-2009, 08:52 PM Thread Starter
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Anybody know the gains on an H-pipe compared to an X-pipe?

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post #11 of 25 (permalink) Old 12-12-2009, 03:12 AM
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Originally Posted by gearhead65 View Post
Anybody know the gains on an H-pipe compared to an X-pipe?
There is none really. An H-pipe will provide better low end torque & there is a change in sound as well.

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post #12 of 25 (permalink) Old 12-13-2009, 06:55 AM
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From all the research I did before I chose my setup, I found that almost all trucks with dual out exhaust you will find an H pipe installed on them, thus because everyone claims it helps with torque, also an H pipe tends to be louder than an X pipe.

The X pipe will be found on most performance car/race applications because it helps with HP more than torque management and only assists with even flow and back pressure to the mufflers. Will not add a whole lot of noise but will give better flow of the overall system.

These are just things I read when I did my research a few months ago, and I am very glad I went with a magnaflow tru x pipe(2 1/2 in and out)


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post #13 of 25 (permalink) Old 12-13-2009, 03:19 PM
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is adding a H or X pipe to a stock exhaust even worth it?
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post #14 of 25 (permalink) Old 12-13-2009, 03:38 PM
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is adding a H or X pipe to a stock exhaust even worth it?
I'd say so, as the stock mid muffler is pretty restrictive. But that being said I wouldn't expect an enormous gain in Hp or torque.

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post #15 of 25 (permalink) Old 12-13-2009, 05:27 PM
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If you are going to add the H or X pipe then have whoever does it do a resonator delete as well and you will free up some room and will get more sound out of it. Not a tremendous amount but enough to tell with sound

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post #16 of 25 (permalink) Old 12-13-2009, 08:41 PM
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Originally Posted by El Tejano View Post
There is none really. An H-pipe will provide better low end torque & there is a change in sound as well.
Sorry please try again...an x-pipe produces more hp and torque everywhere than an h-pipe. This isn't even a disputed point among exhaust experts
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post #17 of 25 (permalink) Old 12-13-2009, 09:52 PM
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I know you did not quote me but I said similar things so....

Like I clearly stated earlier, that is what I have read and if you are such an exhaust expert then maybe you can shed the light on what the purpose of the H pipe application is if it clearly does not provide more hp or torque.

Why would any person/manufacture ever put an H pipe on anything if that was the case, and also since you are the expert I'd like to know why most vehicles that are indended for towing are equiped with an H pipe when there is a dual exhaust present from the factory?

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post #18 of 25 (permalink) Old 12-13-2009, 10:12 PM
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I think the "X" is the natural progression of the original "H" pipes. Both will result in better balancing between the left and right cylinder banks and improve exhaust scavenging. The X is more efficient at doing this than the H. I put an X on my 65 GTO when I had the exhaust fabricated and I like it.

I think many manufacturers use the H pipe because it's esier and cheaper to add to an exhaust than a properly built X pipe. The H is simply a piece of tubing welded in at 90 degree angles between the duals. The X is designed for smoother and more efficient cross flow and required more work to create and install in an exhaust system. OEM almost a;ways goes for the cheaper and easier fix.

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post #19 of 25 (permalink) Old 12-13-2009, 10:39 PM
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I just swapped my Magnaflow axlebacks for their full catback setup with an X pipe. The factory GXP mid pipe runs an H pipe but also incorporates secondary cats and a resonator/mid muffler. The Magnaflow catback does away with the secondary cats and resonator but the drone isn't any worse than the other setup and the WOT sound is wicked. It has almost an "exotic" sound to it. I don't know how else to describe it but it sounds nasty.

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post #20 of 25 (permalink) Old 12-13-2009, 11:30 PM
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Quote:
Originally Posted by OBSSSD View Post
Sorry please try again...an x-pipe produces more hp and torque everywhere than an h-pipe. This isn't even a disputed point among exhaust experts
You may want to reread my post:
I said "Doesn't make that much of a difference" & "An H-pipe provides better low end torque" & "there is a difference in sound"

And in regards to "experts" if it isn't a disputed point, why is it I can Google this subject and come up with all sorts of differing arguments about H being better than X or vice-versa even amongst these "experts".
About the only real consistent consensus is that there really is not that much of a difference between the two, they basically provide the same function but within different rpm ranges of the torque & hp curve.

Hot Rod Magazine, October 2000: A good report on H vs X. It went into great detail on the science behind how and why they work, the dependencies on cam overlap, intake manifold runner length, exhaust header length, diameter, the whole boat. Then they did a comparison on an engine dyno with a 355cid motor - first trying headers with different diameter tubes on dual exhaust with no crossover at all, then staying with one set of headers but adding an H pipe and then replacing it with a Dr. Gas X pipe. They printed tables of RPM, HP and Torque from 3,000 to 6,000 rpm for all of this. They didn't say much about sound quality, just that the X pipe changed the exhaust note to a noticeably higher pitch. The H pipe increased peak HP by only 2 and that was at 5,800 RPM. The H pipe increased torque by a maximum of 8 ft. lbs at 4,300 rpm. The X pipe had a peak increase in HP by 6 and torque only went up by 3 ft. lbs. Interestingly enough the H pipe setup made more horsepower and torque than the X pipe from 3,700 to 5,400 rpm. Or you could say the X pipe did better at under 3,700 and above 5,400. So any gain under 3,700 would be minimal. The article concluded that the X pipe was great for constant high speed operation - like circle track racing.

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