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YOUR RESEARCHFister Mod (DIY) Sound Good or Bad
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Install set this weekend
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I installed a set this weekend on my friends 996 and they do sound decent!
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So I replaced the connecting pipe (1.38") with a larger diameter one (1.75") - like in the original Fister - and the conclusion is that the sound is definitely more throaty - good!
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One thing that came into my head is that the workshop used 35mm pipe (1,37") for connecting inlet and outlet.
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The website is old, but I just talked to Brian and I'm going to order a set next month.
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So I replaced the connecting pipe (1.38") with a larger diameter one (1.75") - like in the original Fister - and the conclusion is that the sound is definitely more throaty - good!
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Just got the Fister Mod style install done at a local muffler shop.
It was a bit rough sounding in the beginning, but it�s growing on me.
What do you think about this sound (cold start):
https://share.icloud.com/photos/008x...yR2SaM3HEULXyQ
Hi, decided to use this thread to express bit of dissatisfaction with the "fister hack" mod I did to my 996.2 - 3.6.
Two things:
First - I don't hear this "throaty" tone, this wheezing sound when releasing the throttle (what I hear is rather smth vulgar not any kind of special sound)
Second - what bothers me most:, on high revs (>5,5krpm), where the exchaust should be just singing, there is simply the noise of air passing under very high speed that overwhelmes everything else. Very loud vacuum cleaner rather than flat 6 reaching 7krpm.... Almost like a supercharger whine, but I dont like it.
I wonder what might have caused it? One thing that came into my head is that the workshop used 35mm pipe (1,37") for connecting inlet and outlet. Would too small diameter cause this effect? (but I read somewhere that people go as low as 1,25")
In general, my observations on Youtube - 996.1 usually sound better with this mod than 996.2, but I've never heard this "vacuum" noises enywhere...
Have you ever dealt with something like this?
^^^ Sounds to me like the shop may not have drilled the correct size holes . The bypass pipe holes have to be large enough for the pipe to fit into then weld it up . Or the holes have to at least be the same ID as the pipe being used . Have they ever done this mod before ?
They,ve drilled a hole, put pipe inside and weld around it (the hole itself does not limit flow). The quality of welding is rather high - this shop never done this mod for 911, but they are considered as professionals on local market...
^^^ if all 4 holes were drilled correctly to accept the bypass pipes then I have no idea why you are getting the results you have . Good luck solving the puzzle .
Yup, I think I'll go and "boroscope" all of connections
If it is ok everywhere, I'll try to go with 1,75" . I wanted to keep this "lesser loud", but maybe its not an option.
I'll update the thread, but it won't happen anytime soon.
In meantime - if anybody had similar issue - please let us know!
I think it sounds great, man! Mine sounds same. Just enjoy a little more sound. These cars are not meant to be too throaty� You don�t want to wake up the neighborhood. It�s a classy car, keep it that way.
It took me a while, but I love the sound now. Let it go 🤣
The soud itself is good, just this whistling vacuum above 5,5krpm (starting around 4s of vid) makes me wonder if it is how it is really supposed to be... Do You have same effect on high revs?
After 5.5rpm, I just hold on to deer live and trying to stay on the road, everything is in the state of trance and I don�t notice any strange sounds. I don�t do that too often for long either.
I installed a set this weekend on my friends 996 and they do sound decent! I'm in the process of gutting the stock exhausts now to see what they sound like. It's crazy how stifled these exhaust are......amazing they even flow.
So I replaced the connecting pipe (1.38") with a larger diameter one (1.75") - like in the original Fister - and the conclusion is that the sound is definitely more throaty - good! Unfortunately, the high revs "vaccum" whining is still there - what a disappointment...
I think it might be something wrong with the inside of the muffler(s), because I ran without them (a homemade exhaust bypass) - and nothing like that happened (by the way - with the bypasses - high RPM - great! low RPM - a pain in the ears).
A bit strange, because before I did anything, those were stock and I didn't hear any symptoms...
I like the idea of a bit more throaty, more flow, but I'm stuck with a wife who only nags me about one thing. I don't really hear what the hell she is whining about, but when she writes it down and sticks the piece of paper in my face I am reading that I don't hear worth a ****.
Between racing motocross, airplanes and the amazing music of my time, she might be on to something. I'm wearing noise cancelling Bose headsets when I'm doing high speed driving in my little rocket. Still get lovely flat six tone, without the road noise.
The stock muffler's design looks like something straight out of Peugeot's play book. Other threads about the Fister mod indicate more cabin noise, as do the Fabspeed and Soul mufflers. I'm not looking to annoy the neighbors or wildlife. Is there a solution that increases flow without increasing dB?
Although cats will certainly help the stock mufflers are extremely stifling and are still your pinch point! They just do not flow worth a $hit!. I cut open a set and there are 3 chambers inside and found that how it even flows is amazing. No wonder the motor runs so much better with a free flowing mufflers! It's crazy they can even breathe.
I am pretty sure the reason he said stock mufflers was my restriction "
Is there a solution that increases flow without increasing dB?"
No one is publishing dB of their muffler v stock muffler. From what I've seen, more flow means more noise. I'd like to be able to try a better flow muffler before plunking down cash.
I've done some things with exhaust systems in my past and this design makes a lot of sense to me.
http://afterhoursautomotive.com/Pors...20exhaust.html
The website is old, but I just talked to Brian and I'm going to order a set next month. The current price is $1399. At this price I'm willing to see how loud they are.
I was planning to "fister mod" my 996, but ended up trying different back boxes and even straight pipes with the original cats (3 cylinders per pipe) and was still disappointed with the overall soundscape, the high-rev throttle lift -> vacuum sounded terrible. Only way for me to fix this was to install a x-pipe, which did come with high flow 200-cel cats and less muffled back boxes. All parts came from Top Gear exhaust in UK and I'm now super happy with the soundscape of the car:
You Tube
The sound somewhat resembles a GT3, which I definitely do not hate. Sorry for the wind noise in that clip, but it's the only one that I had.
I mentioned the high flow cats because that�s exactly what they do. Improve flow.
when researching all the published numbers from the exhaust producers I suspect that the cats seem to be the biggest restriction in the whole system w the best possible gains when swapped.
although to be honest I wouldn�t really trust Numbers out side of an actual dyno. Even then many shops say they don�t see those published gains when independently dynod.
probably best to chase the desired sound you want rather than any gains. JMO
As I explained in my original post, "cats will certainly help" but if you are going after sound, the mufflers are your focal point.....so with "high flow cats" because it's pushing more air, you will have more sound.....you can't have one without the other.
It is more of an academic exercise -- with enough baffles and muffling you could reduce the sound of a car at WOT to a whisper without any significant restriction. It would just take a very large volume of material to get the job done.
Imagine a pipe that immediately splits into 100 3" diameter straight through packed mufflers.
