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YOUR RESEARCHGundo or Fister Mod on aftermarket exhaust like Agency Power on a 996
Leading reported evidence
Use stockers
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Gundo or Fister Mod on aftermarket exhaust like Agency Power on a 996
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Leading evidence: 'Use stockers' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace stock cats' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
If you're finding the levels still too quiet for your tastes, many have reported additional sound gains by replacing the stock cats.
Gundo or Fister Mod on aftermarket exhaust like Agency Power on a 996
Use 1.25" piping
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Suggestion
I did a Gundo hack on a set of Agency Power mufflers for a friends car a few months back using 1.25" piping.
Gundo or Fister Mod on aftermarket exhaust like Agency Power on a 996
Use ones
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Suggestion
If i come accross some used ones that i can pick up for a few hundered bucks i think ill go with that.
Gundo or Fister Mod on aftermarket exhaust like Agency Power on a 996
Use ss tubes and ss welds
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Suggestion
If you can follow it through all the way using SS tubes AND SS welds.
Gundo or Fister Mod on aftermarket exhaust like Agency Power on a 996
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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
11 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Outcome without a verified action link
It sounds good with no drone but still not loud enough for my taste.
Hello All - I have been jumping around searching for the perfect exhaust - Tried the Fabspeed Supercup that sounded awesome between 3-7RPM's but left my ears ringing between 2-3K. I tried the Fister Mod which sounded great but those cans weigh a ton. I recently scooped up a pair of Agency Powers for fairly cheap but I think I need somebody to follow me to let me know if it sounds any different than stock. Great news is Drone is basically non-existent but so is increased sound......Long way to the point but has anybody tried the gundo or fister mod to an aftermarket exhaust like the Agency that is too quiet for my taste but love the no drone and the 20 lbs off the back of my already to heavy Cab.
Any responses appreciated
You can do a modified PSE and get a decent sound. Its a little louder than the PSE mod and different than the bypass pipe mod (not the muffler bypass pipes you see for sale that eliminate the muffler).
While you have the two muffler outlets open for your mod (one is a "plug" if you dont have factory PSE) and can see inside the muffler, there is a solid wall seperating the chambers. You can experiment with different size "holes" in the wall until you get the sound you want. Your actually doing an internal muffler bypass instead of external one. I know it may be hard to understand without seeing pictures. I was able to do this myself. I will probably just cut the muffler skin open next time to make it easier. I got this idea from another poster who opened his muffler to repair it not mod it.
Its a little louder than a PSE but not annoying. No drone. I plan on experimenting by enlarging the hole in the muffler wall until I get the perfect sound I want. I will try and dig up some photos or post a sound clip on Renntech if you want. I had the PSE "hack" done first but was not happy with the quality of work or the sound. Thats why I re-did it myself and added the internal mod.
I did a Gundo hack on a set of Agency Power mufflers for a friends car a few months back using 1.25" piping. It definitely made them a bit louder without introducing additional drone.
Im working on making a set of stock mufflers with an easily removed access panel where you can remove or put back in the internal muffler wall. Might even try a half wall. Im using stock mufflers even thought their heavy because their cheaper to destroy. Ive seen crappy used stockers for @$100 a pair.
I did the Fister mod on my gemballa cans with a 1" piping. It sounds good with no drone but still not loud enough for my taste. I think im gona go with 2" next time i have my cans off.
I've contemplated on doing this mod when I had my Agency Power mufflers but ultimately sold them and now have the Tubi's.
I've also contemplated on just gutting the stock cans as others have reported some weight savings doing that, but I was concerned that I might get highway droning as well.
If you're finding the levels still too quiet for your tastes, many have reported additional sound gains by replacing the stock cats.
I'm going to be using my Tubi's with aftermarket crossover pipes and hoping it will be a good balance without being "too loud".
Hi alpine003
I have also been considering getting race cats but the darn things are so freaken expensive. If i come accross some used ones that i can pick up for a few hundered bucks i think ill go with that.
I agree. If the crossover pipes didn't have as many bends in them, I could see more people just doing a diy with their own piping and universal 200 cell cats as those are still somewhat reasonable compared to a whole Porsche specific system.
I guess you can always hack up your stock cats and replace them but then you still have the pipe bends and such that is still not optimal.
This site lists them under $200 each so for a Porsche system, you're probably paying close to $1000 for the piping/bung holes/flanges by my calculations.
Edit: Forgot to include link:
http://www.mil-spec.org/2.5-200-Cell-Weld-In-Cat.html
