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YOUR RESEARCH200 Cell Cats + Gundo = Too Loud?
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Suspected cause · Original poster
I did some highway pulls today and, I'm not sure if this is placebo due to increased sound, but I do feel like the car pulls a bit harder and wants to rev a bit more (I suspect due to the cats, if it is actually real).
Replace cats and mufflers between oem and aftermarket
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But I never experimented with changing cats and mufflers between oem and aftermarket to see the differences in sound when I moved from oem cats/mufflers to FVD 200 cell cats/mufflers.
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Replace cats and mufflers between oem and aftermarket
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But I never experimented with changing cats and mufflers between oem and aftermarket to see the differences in sound when I moved from oem cats/mufflers to FVD 200 cell cats/mufflers.
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I think you could try replacing the cats and see if that tames it down a bit.
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A bit of information that would have been valuable to you before you did all this: you can increase cabin engine sound by removing and plugging the intake resonator and replacing the throttle body inlet with a silicon tube.
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Suggestion · Original poster
With your setup, are you running an x-pipe with the FVD 200 cell cats, and Gundo'd mufflers, or stock mufflers?
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But I never experimented with changing cats and mufflers between oem and aftermarket to see the differences in sound when I moved from oem cats/mufflers to FVD 200 cell cats/mufflers.
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A bit of information that would have been valuable to you before you did all this: you can increase cabin engine sound by removing and plugging the intake resonator and replacing the throttle body inlet with a silicon tube.
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Suspected cause · Original poster
I did some highway pulls today and, I'm not sure if this is placebo due to increased sound, but I do feel like the car pulls a bit harder and wants to rev a bit more (I suspect due to the cats, if it is actually real).
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Hey everyone,
First timer here. I just recently purchased an 03 C4S (first pcar ever) and am in LOVE with the car! It's so beautiful in every way.
I find myself in a bit of a situation...I wanted to increase the sound a bit, and hear more of it in the cabin. I took the car to a local exhaust shop and they did a 2" Gundo Mod on the OEM mufflers. I had also purchased the
Crossover 200 Cell Cats from TopGear
as I thought it would be a good idea to do everything in one shot.
Now I find that the car is way too loud, to the point where I'm hesitant to really just push the car around like I used to. There is very little to no drone which is great but I feel like it's simply too loud for daily driving. It could also be that because it's such a stark difference from the full stock setup that I may just not be used to it...
On top of that, I now find that the tone has completely changed and it's so raspy, tinny and guttural sounding which I'm not the biggest fan of. At WOT, it sounds a bit ricy and like a Honda...I was hoping to get a higher pitched, motorsports type sound while making it a bit louder.
My questions are:
A) What do you think is the contributor here to the change in tone? Gundo or Cats?
B) Do you have any suggestions for moving forward? I was thinking of either just putting the stock cats back on or keeping the 200 cell cats and finding another OEM muffler...worth trying an x-pipe vs crossover?
Would love to hear your perspectives and if anyone's ever experienced anything similar!
Thanks.
Hmm�
I have just the Gundo, and it can be loud - at WOT at higher revs and in a tunnel, yeah, it�s loud. But otherwise just driving around, even in a spirited fashion, it�s not really loud.
I think you could try replacing the cats and see if that tames it down a bit.
The stock exhaust is very quiet.
Is this how the Gundo hack was done?
Thanks - I was considering just swapping the cats back and seeing how that sounds. And I'm not 100% sure but I believe that's how the Gundo was done, yes. I can potentially get used to the volume but the tinny sound kills it for me. It sounds ricy.
Yeah, that�s a good idea. My Gundo with stock cats sounds more guttural than ricy or tinny, although my 99 5-chain does still sound raspy on deceleration at lower RPMs (1000-2000).
A bit of information that would have been valuable to you before you did all this: you can increase cabin engine sound by removing and plugging the intake resonator and replacing the throttle body inlet with a silicon tube. I did this as well in my car, but it�s overshadowed by the Gundo hack (the intake mods sound best at WOT, which is when the Gundo is loudest.
Thanks for that tid bit - I'll look into that. I can also try to get a few sound clips as well. Do you think an x-pipe 200 cell cat would remove any of the tinny sounds?
BTW, if anyone takes sound clips, to measure loudness, post the distance from the tailpipe to the microphone. Standard practice for loudness measurement is 1-meter away (loudness decreases 6dB every doubling of distance).
I have stock cats and gundo and love the sound. Very 'gutty' sounding to me and not a rice burner coffee can sound. Love it when I stomp on it! I have no experience with any other mods but when the cats give way I'll go the 200 cell cats as well so this will be interesting to follow what others say too. Or I hit the lottery and have Dundon Motorsports build me a complete system
OP - Welcome. Pictures or it didn�t happen. Depends on what you�re used to with previous exhausts. Gundo with 200 cell seems to be a most popular sweet spot. Below 3200 rpm the sound should be pretty normal. You can drive around the �hood and the grandmas won�t be accusing you of being a hooligan. Once you get above 4000 it�ll get �loud�, or what I call �just right�.
Thank you for the welcome! Haha will try to get some footage this week. I'm going to also confirm the Gundo configuration with the shop...I suspect it's what Mike Murphy posted above.
One of my issues with the sound is tone...it just sounds so tinny at WOT.
Does anyone think an x-pipe cat might remedy the tinny sound I'm experiencing? I came across this video and that seemed to help this individual.
Video
Yeah, Mike's gundo hack sounds great. A deeper exhaust sound than oem when it idles and when he is not on the gas hard. It opens up to a great sound that is louder when he gets on the gas hard. No tinny sound nor drone inside or outside if the car.
Don't know much about your cats, but if you just want a better sound that is controllable with your throttle inputs, the gundo hack with oem cats may be your ticket.
The advantage to a good set of lightweight 200 cell cats is weight loss, more mid and high range power and possibly sound variation. But I never experimented with changing cats and mufflers between oem and aftermarket to see the differences in sound when I moved from oem cats/mufflers to FVD 200 cell cats/mufflers.
I think I'm going to have to try a few combinations. With your setup, are you running an x-pipe with the FVD 200 cell cats, and Gundo'd mufflers, or stock mufflers? I did some highway pulls today and, I'm not sure if this is placebo due to increased sound, but I do feel like the car pulls a bit harder and wants to rev a bit more (I suspect due to the cats, if it is actually real).
I have a 2006 version of the FVD 200 cell and FVD performance muffler. Sound great, performs great, big weight savings and has been durable as he'll. Software will help with throttle response and to pull it together. Cats are arguably the biggest performance upgrade. Comes down to what you are looking to accomplish. Plenty of flavors.
https://www.fvd.net/us-en/21011122/s...-mufflers.html
If you have an e-throttle car, a tune from a reputable software company can provide more immediate throttle response. Which is a huge plus. It can also help tie in your headers, cats and intake to function more effectively. Don't know what the HP/TQ gain may be, but mine improved throttle response and helped to improve midrange power delivery.
Keep in the back of your mind that turbos benefit the most from a tune in power gains. Naturally aspirated engines dont benefit nearly as much as turbos. Many performance specs suggest a 20-25 hp/tq gains from ported equal length headers, 200 cell cats, free-er flowing mufflers, IPD plenum, gt3 throttle body and tune. But you are looking at $10k in total. Proper cat and header upgrades may account for a good portion of it, with plenum, throttle body and tune filling in the holes.
Take a look at FVD Brombachers website. Not only have they been racing 911s forever, their exhaust systems are made by M&M who manufactures the Porsche Motorsports exhaust systems. They also have software that will tie in every exhaust component, IPD plenum and GT3 throttle body as well.
Sure, there are plenty of other companies as well that you undoubtedly hear about on this thread.
Take your time and line your ducks up before you pull the trigger. All of it is silly expensive especially if you don't think it thru and do it right the first time.
Good luck.
Fwiw, it's always a good idea to bullet proof your engine first before spending silly money on exhaust systems, fancy wheels and interior bits. Nobody want a pretty paperweight taking up space in their garage.
The sound is just not appealing....missing a pleasing tone. If I had to describe it to an acoustics engineer I'd say it has the wrong frequency content
Hey everyone, quick update.
The weather has finally cooperated somewhat and I was able to take a few short clips of the car. This is actually my first time hearing it engine warm and from outside behind the car (as opposed to cold and in the cabin).
While the volume is night and day louder compared to stock (something that I'm getting more used to now...), I must admit that I think there may have been a slight overreaction on my part lol! Hearing it both in person and in these clips, I think it actually sounds pretty good.
Would love to hear your opinions. Going to try and take longer/better clips soon as well.
You Tube
You Tube
You Tube
It sounds bad *ss. That extra spunk is the cats. I was behind a Cayman on the track once that had that same sound. The flat-6 has a great sound when it�s opened up. The 996 sounds as good as any 911.
The Gundo is quieter and a good compromise for a neighbor that complains. If nobody complains, go with what you prefer.
I think it sounds good.
I had the gundo hack done, and initially I didn't like the way it sounded either, but after driving it a bit I started to appreciate the new tone.
Probably leave it. If you insist on mild the Top Gear milds mufflers really are and at a fair price. They are on Youtube. My daily a Holden Senator (US Chevy SS) was way loud post blower and exhaust. I had no issues untill a job change, and moving into an apartments, complex in a New State where the car was Db inspected and failed. I still got 5 years of fun. I tend to agree with the posts a 911 should sound like one. If you love your 996 like i do mine. I tends to obcess and adjust it all to my taste. Last year I stopped, service and enjoy it.
