Gundo Hack "REVERSE"?
Instructor
Joined: Aug 2010
Posts: 154
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From: Central North Carolina
Crossover pipe, X pipe, same thing. You're the first I've heard that got rid of the center silencer AND did the Gundo Hack on a 997.2. That must be loud as ****, although I wouldn't know, as I replaced the entire system.
Here is a pic of my Tubi exhaust, where you can see the crossover/x-pipes that eliminates the center silencer on 997.2's. You can also see the side cans that were also replaced with the Tubi cans.
Here is a pic of my Tubi exhaust, where you can see the crossover/x-pipes that eliminates the center silencer on 997.2's. You can also see the side cans that were also replaced with the Tubi cans.
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Joined: Oct 2012
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Banned
Joined: Feb 2012
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From: Nashville, TN
I'd give up a few inch lbs. 
of torque to let the engine breath better on top. You drive you car above 2,500 rpm anyway. If you drive it spirited on the track or on the road you be over 3,000 rpm's 99% of the time. I have heard that the x-pipe reduces torque. Typically, it's the headers that affect torque the most.
of torque to let the engine breath better on top. You drive you car above 2,500 rpm anyway. If you drive it spirited on the track or on the road you be over 3,000 rpm's 99% of the time. I have heard that the x-pipe reduces torque. Typically, it's the headers that affect torque the most.
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From: Charleston, SC
Hate to point out the obvious but just because the crossover pipes form an "x" does not make them "X-pipes". Crossover pipes and X pipes are NOT the same and affect exhaust flow very differently. The X junction is congested on the Porsche setup and does not provide the accelerated exhaust flow like on an American muscle car. My setup is not loud at all and has a nice raspy sound at cold start that quickly settles down to a slightly louder than stock idle that has just enough throat to let you know it is not stock. On the road the noise is muted on the inside (no drone) and mimics the PSE for sound without the convoluted and expensive valve activation. WOT brings on a strong sounding exhaust that I would stack up against any $$$$ aftermarket system.
It clearly refers to replacing the center silencer on 997.2 cars.
In a later post, I provided a pic of the Tubi exhaust showing the pipes that eliminate the center silencer.
If you're referring to internal muffler construction, or perhaps adding an X pipe on a Corvette, perhaps could post a link or a pic or 2 that addresses whatever it is you're talking about or take issue with?
That pertains to my post?
Instructor
Joined: Aug 2010
Posts: 154
Likes: 1
From: Central North Carolina
Please reread post #9, my original post in this thread.
It clearly refers to replacing the center silencer on 997.2 cars.
In a later post, I provided a pic of the Tubi exhaust showing the pipes that eliminate the center silencer.
If you're referring to internal muffler construction, or perhaps adding an X pipe on a Corvette, perhaps could post a link or a pic or 2 that addresses whatever it is you're talking about or take issue with?
That pertains to my post?
It clearly refers to replacing the center silencer on 997.2 cars.
In a later post, I provided a pic of the Tubi exhaust showing the pipes that eliminate the center silencer.
If you're referring to internal muffler construction, or perhaps adding an X pipe on a Corvette, perhaps could post a link or a pic or 2 that addresses whatever it is you're talking about or take issue with?
That pertains to my post?
From your posts I'm still not convinced you know the difference between an crossover setup and an x-pipe.
On the Fabspeed website there is a picture of their x-pipe with the center junction. Your Tubi crossover pipes are not an x-pipe.
I am basing my opinion on the efficiency of an x-pipe on what Sharkwerks published in a detailed tuning guide based on their experiences with modifying the 997.2 and what works and what doesn't. This is available (free) on their website and is a very good guide. They do not recommend an x-pipe for the 997.2.
Fabspeed website: https://www.fabspeed.com/carrera_2009.html
What Sharkwerks says about x-pipes in ther tuning guide:
Center muffler X-merge bypass, or replacing the first (center) muffler with straight-through tubing and combining the two sides to an "X", then using the side mufflers as originally designed. This was our first design and while it looked nice, it actually did not make the car much louder than stock. It also creates a bottleneck in the exhaust flow. No matter how well these "X-intersections" flow, they will never outflow two independent, mandrel-bent tubes. This explains the quieter tone and would probably result in less horsepower than the latter idea.
Racer
Joined: Sep 2010
Posts: 314
Likes: 15
From: Maryland
I was lucky enough to find a set of already modified "Gundo" cans from a 6spd forum member. I kept my stock cans in case I ever wanted to switch back. I've had the gundo cans on now for several months and still like them a lot. There is really only a noticeable difference on cold start and at wide open throttle. Other than that it is totally stock sounding. No drone or rattle in any way. I'm sure I'll end up selling my stock mufflers to someone soon so they can be modified. I can't see going back. Inspection in Maryland caught nothing, and the car throws no error codes at all. I'm very satisfied!
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From: Charleston, SC
https://rennlist.com/forums/997-foru...ielations.html
You can rest easy now. I do appreciate your concern, though.
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Thread Starter
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Joined: Aug 2012
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From: So.California
I was going to do just that, I just did not want them to know I was getting this done just in case they said YES! It would. Then they would use this against me on a claim. But I did call them and my advisor said maybe on an aftermarket exhaust But not on the Gundo hack he said its just for sound.
Thanks for the advice now I feel better.
Steve
Thanks for the advice now I feel better.
Steve
Last edited by 911Steve; Jan 4, 2013 at 07:50 PM.
Thread Starter
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Joined: Aug 2012
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From: So.California
Ok, I got the Gundo Hack done today by Chris Sterling at "Grand Auto Works" in Irvine Ca. Did a 2 inch wasn't sure what I wanted but Chris recommended the 2 inch. He said this is what most of his customers Are getting done. It was a big improvement over stock, as others have said the exhaust comes alive. No drone what so ever at freeway speeds, you instantly here the improvement when just going through gears even on slow driving. I have a cab and maybe I can hear more than the coupe would. On the drive home also put the top down, very exotic sounding over stock. BTW, Chris is a very nice stand up guy and was a pleasure to have him conduct the work. I highly recommend Chris to anyone wanted this done.
Steve
Steve
Thread Starter
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From: So.California
Thanks again Andrew for the info directing me to Chris Sterling for this work to be done. Keep us posted on the outcome of your new mods. Andrew just curious did you have the 2 inch done to your mufflers?
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From: Overland Park, KS
997.2
Did the Gundo first and it didn't get me what I was looking for.
Next added the Sharkwerks X pipe, cross-over, or whatever it's called........
That got me where I wanted to be. It is not loud as sh*t. In fact my wife didn't even hear the difference unless I went Sport Plus and floored it.
If I did it again, I would start with the center muffler delete first. My gut says that it would be enough and you wouldn't have to mess with the Gundo on these .2 cars.
Did the Gundo first and it didn't get me what I was looking for.
Next added the Sharkwerks X pipe, cross-over, or whatever it's called........
That got me where I wanted to be. It is not loud as sh*t. In fact my wife didn't even hear the difference unless I went Sport Plus and floored it.
If I did it again, I would start with the center muffler delete first. My gut says that it would be enough and you wouldn't have to mess with the Gundo on these .2 cars.
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