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Exhaust mod - clarification of Gundo and Fister

Posted: Sun May 27, 2018 3:22 pm
by Water Hound
A lot of confusion swirls around the names of two common exhaust mods. The "Gundo Hack" and "Fister mod" are two completely different mods which result in different exhaust notes.

The Gundo PSE style mod
Gundo PSE style mod
Gundo PSE style mod
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This is a Porsche Sport Exhaust (PSE) style exhaust without the inline solenoid switch enabling it to be opened or closed. With a Gundo you're open all the time - perfect! This mod is a partial muffler bypass. All gases pass through at least a portion of the muffler. Some of the exhaust takes a shorter trip and only flows through the first resonant chamber of the muffler then goes straight to the output pipe. To do this mod you open up the capped exhaust port in the muffler and connect it to the output pipe of the muffler with a stainless tube. The larger diameter the tube, the deeper and richer the exhaust note. My 2004 cabriolet has the Gundo hack with a 2" pipe. Because all exhaust passes through at least a portion of the muffler the sharper bark of the Fister mod isn't present. Glorious sound, no drone and amazing under full throttle.


Second, the Fister mod
Fister mod
Fister mod
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Whereas the Gundo runs all exhaust through at least a portion of the muffler, the Fister mod is a true muffler bypass for a portion of the exhaust The input and outflow pipes are joined with a tube directly. Results are a bit louder, raspier and there is a bit more of a sharp bark to the exhaust note without being too loud. The larger the diameter of the pipe used, the deeper and throatier the exhaust note. This is the mod that will find a home on my C4S in the near future and is likely the perfect option for a coupe. The Fister mod is done professionally by Darren Fister and you can see his work at fdmotorsports.net. While many people do their own hack for a Fister mod, FD offers a guaranteed job with a great selection of finishes.

To sum up, these are two excellent exhaust modifications. While they don't offer real horsepower gains, they will definitely sound at least 50 hp faster. As a warning, your fuel economy will suffer because you won't be able to stop yourself from putting your right foot down a lot more aggressively. Enjoy!

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Wed May 30, 2018 9:04 am
by 5chn3ll
Nicely put.

TL;DR: Do the Fister, not the Gundo

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Fri Jun 08, 2018 9:36 pm
by flatsix
20160204_161944.jpg
I could not decide so I did both. it's not as deep sounding as I thought it would be but that could be due to the headers. It is a huge improvement in sound over the un modified stock exhaust.

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Thu Jun 14, 2018 7:26 pm
by Water Hound
flatsix wrote: Fri Jun 08, 2018 9:36 pm 20160204_161944.jpg

I could not decide so I did both. it's not as deep sounding as I thought it would be but that could be due to the headers. It is a huge improvement in sound over the un modified stock exhaust.
Let's call it the flatsix spaghetti mod! Quite a piece of modernist sculpture there.

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Tue Jun 19, 2018 8:05 am
by sweet victory
Water Hound wrote: Thu Jun 14, 2018 7:26 pm
flatsix wrote: Fri Jun 08, 2018 9:36 pm 20160204_161944.jpg

I could not decide so I did both. it's not as deep sounding as I thought it would be but that could be due to the headers. It is a huge improvement in sound over the un modified stock exhaust.
Let's call it the flatsix spaghetti mod! Quite a piece of modernist sculpture there.
I had to go to urban dictionary for this one. We should call it "The Double Twister Fister"

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Wed Jun 20, 2018 12:17 am
by flatsix
I will admit it looks like a lot but installed all you see is the stock exhaust tip. All you hear is a raspy slightly tinny bad to the bone exhaust tone. I've watched many youtube 996 rally car vids and it sounds pretty much like those except I'm never on a narrow dirt road. I'll work on getting a vid attached but I'll say right now just putting a picture up was a stretch of my skills for me.

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Mon Oct 01, 2018 8:39 am
by Einsteiger
Thanks for the clarification. I had always assumed that these were the same thing, just that Fister does a very professional job. NOW I know the difference. I'll probably go with a FD mod over the winter, as my 911 is a tiptronic - not that it makes a difference. I like the black finish that FD can apply ;)

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Wed Oct 24, 2018 12:59 pm
by Spiegelei
I'll give my .02

If you want a noticeable exhaust change don't go the Gundo route.. it maybe changed exhaust volume by 5% under 5k rpm and maybe 15% towards redline. It sounds the same inside vs stock to me and if I'm doing a muffler modification I want to be able to actually notice it. I paired the Gundo mufflers with a catless x-pipe and it certainly woke the car up in sound and drastically changed exhaust pitch (in a good way).

I wanted more, so I bought a second set of mufflers and did the fister mod. Paired with the catless x-pipe it's perfect for me. No drone, good noise, quiet hot idle. I did a comparison of the two mufflers in the videos below. Both shot with the same camera at the same location.

Image

Gundo Mufflers, Catless X-Pipe


Fister Mufflers, Catless X-Pipe

Re: Exhaust mod - clarification of Gundo and Fister

Posted: Sun Dec 23, 2018 12:39 am
by Water Hound
Did the Gundo hack PSE style mod on the cabriolet. Agree that it would be pretty mild on a coupe and may not be worth the effort. With top down driving though, the Gundo is a really sweet sound and is just perfect for me.