[QUOTE=cannga;2824892]Please look first at post #3 below for my professional :-) guide to exhaust auditioning and selection.

First, my "credential" LOL: I am a dedicated and seasoned audiophile who cares very much about sound. When I searched the web for opinions about car exhaust in the past, I had a lot of difficulty understanding the reviews, especially when someone would wax poetic about some exhaust system without ever *describing* what it sounds like (!), so following is my attempt to describe what I hear. I have listened to many exhaust systems in person so IMHO I have a good frame of reference as to what each of them sounds like. Later, I will add some comments on what I've learned about other aspects of exhaust systems, such as power gain, torque loss, drone, etc. The hope is simply to help anyone who is new to this.


When you move from the stock system to this, you will likely notice that it's a day and night improvement over stock exhaust. It is quite frankly one of the most beloved mods in my car, up there right next to the Bilstein coilover. When I evaluate exhaust, there are 3 parameters I listen for, so here I will compare stock vs. Cargraphic on these 3 parameters:
1. Loudness: I would rate the Cargraphic Loud as high-medium in loudness. Don't let the name fool you, the Loud version of this exhaust is not that loud and about 10% of the times I wish that it is even louder. OTOH another 10% of the times I wish it *less* loud :-); this is simply the nature of the beast, we don't always want the same thing all the times. For example, the AWE exhaust has similar loudness to this, and the GMG is louder. No right or wrong, just pick what you prefer most here. And below are my rankings of loudness, approximately based mostly on what I heard, and also on what people I think trustworthy have reported. Don't be upset if you disagree please, this is simply my opinion based on the best I could hear, and is subjected to changes any time.
1. GMG - this is an exciting and great sounding exhaust, but loud, very loud. Make sure to listen before you buy.
2. A tie between AWE and Cargraphic Loud; BBI would probably be in this group also.
3. EP2
4. EP1
5. Tubi - very quiet, too quiet for my taste and very little low frequency rumbling.
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Excellent write-up on exhausts for turbos. Gathering these together for comparison has long been overdue.
On your loudness grade, can you grade on a 1-10 scale the loudness of EP1 vs GMG?
I have an EP1, giving my factory exhaust a 1.0, the grade with my EP1 is now a 5.0 in increased loudness. Sounds like from what you have written you might grade the GMG a 10.0 on a 1-10 scale or maybe slightly lower
My loudness 1-10 grades were set from idle sound and for sound cruising 25-40m/h thru residential neighborhoods.
I think from limited sound bites I've heard, that the GMG gives the turbo the closest sound to a NA engine over any of those other exhausts you listed. What do you think

 

Hi John, first let me reiterate that I am extremely hesitant to recommend any exhaust, especially a loud and aggressive one like the GMG, to anyone without that person actually listening to it in person. That said, yes, quite a few of your comments about the GMG exhaust are correct.

First if you want that V8 rumble, then true, the GMG comes closest to that sound than any other that I've heard, including my own Cargraphic. The GMG sound is very deep, it rumbles all the times, and to add to the sound effect, it pops and spits loudly occasionally like it's angry about something :-). If you want to clear your eardrum physically, this is the exhaust as it sounds very race-car like. I think the sound reflects the guys at the shop, who of course race professionally.

Porsche's stock 6 cylinder exhausts, and some European exhausts, have this "hollow chamber 6 cylindish" sound that you described in the past (I had a chuckle when I saw this - very true). You will not hear any of this with the GMG. It is all deep and power and raw.

As for whether it replicates a NA engine. Yes and no. Yes it comes closer than any other; no it doesn't quite "howl" (think of a wolf) with high frequency as you go up the rpm, the way a GT3 or Lamborghini (my all time favorite) would. This is just a reflection of a couple things about the Turbo engine, one the turbine muffles the high frequency component more and this loss is not recover-able, and 2, the Turbo engine doesn't rev (IMHO) as instantaneous or as fast as a NA engine would.

The big question for the GMG is the loudness. It is to me more for the weekend car or race car, then for a daily driver, especially if you are stuck in traffic daily. OTOH If you *are* looking for this degree of loudness and V8 like deep rumble, you've come to the right exhaust. It is also very beautifully made. Is there anyone close to your area with this exhaust? Will you be in Southern Cal any time soon?

 

wow. a five year thread resurrection, and you didn't miss a beat. ( you la session guys ) all kidding aside. i truly enjoyed reading this thread, the (car) graphic detail, and particularly your obvious ability to detect sonic nuance. the most comprehensive and exhausting ( in a good way ) review i have seen! my only difference with what you posit however has to do with "drone", or that one need cruise above 3k rpm to mitigate *it*. i just don't hear it. since i genuinely feel my old trusty 996t with a pre history cargraphic, doesn't drone,.. but no matter! i do share your love of the cargraphic note! and i try to stomp on it daily.

how about those kanan dume tunnels for a lil "sound check?" huh?... scare a tourist daily, i say. cheers...

 

The big question for the GMG is the loudness. It is to me more for the weekend car or race car, then for a daily driver, especially if you are stuck in traffic daily. OTOH If you *are* looking for this degree of loudness and V8 like deep rumble, you've come to the right exhaust. It is also very beautifully made. Is there anyone close to your area with this exhaust? Will you be in Southern Cal any time soon?[/QUOTE]

Guess, I can't get you to commit to a 1-10 loudness grade on the GMG vs EP1 (5.0 grade) vs stock (1.0 grade) which to me means the GMG is most likely way over 10.0. If GMG is that loud I best stay away from it with the wife and neighbors already complaining about early morning EP1 startups and neighborhood drive-thrus.

 

John, especially because I know of a couple of people who have actually switched out of GMG because of the loudness (while others love it - strictly personal preference, no right or wrong), I would think it's mandatory you take a listen in person if that's the direction you want to go. If you use car as a daily driver and go to work very early in the morning, yes I think it could be an issue in a noise-sensitive neighborhood.

IMHO, loudness is the make or break point to any exhaust, as opposed to sound quality for example. If sound quality sucks, one could sort of put up with it, but if loudness is not right, you are talking about selling the exhaust, and these things are not cheap.

BTW, I recently went through the coolant leak nightmare that you had. Thankfully I too had extended warranty (mine is with Fidelity) because the bill was not cheap ($4-5K). I was very disappointed but boy I missed the car dearly the time it was gone.

 

True - I never did understand the value of after-market exhaust until I had this Turbo. Made the switch and have been amazed by the psycho-acoustic value ever since. Feel the same about 991 - am sure it's going to be very fast and many aspects are better, but I have no itch whatsoever to switch.

Let's have a toast to the good life, good driving, and good sound!

 

"Clink" ... lifting my glass to that !

 

BTW, I recently went through the coolant leak nightmare that you had. Thankfully I too had extended warranty (mine is with Fidelity) because the bill was not cheap ($4-5K). I was very disappointed but boy I missed the car dearly the time it was gone.[/QUOTE]
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EasyCare extended warranty for me would not cover the blown coolant rubber hose. My cost $2600 for engine drop and all hoses replaced. Tried to get Fidelity, but they told me they were not covering turbos anymore with an extended warranty with factory warranty expired. Just renewed my EasyCAre for another couple years. Perhaps if I would have bought Fidelity at the time of the car, things would have been different.
Important question: Are you telling me Fidelity covered the expense (engine drop) to replace a blown rubber hose???? Not even sure if factory warranty would cover that. .
Back to the loudness 1-10 grade........still no grade from U convinces me that your loudness grade for GMG would be a 10+ , like a 20 with stock at 1.0 and EP1 at 5.0

 

John, my coolant leak was different. It is from 2 metal pipes rubbing each other at a different place from yours, but also in the back part of the engine. I believe these pipes carry coolant from back to front then back. It is true that had it been rubber, Fidelity would not have covered it. The headache that resulted is the same: engine was dropped to fix the issue. Your thread on that subject was very helpful and I would like to thank you for that (I had them change spark plugs and drive belt on my dime when engine was down). I was very disappointed but also understand that things break and now that it's fixed, the love is the same and this baby is again a keeper.

And I understand your exhaust question very well - I was (and am) very hesitant to give rating numbers because I really don't want to give people the idea that I have professionally measured sound levels. Even with measurements, it's dangerous to rate subjective loudness (as opposed to objective sound pressure level in db) in scale of 1 to 10. You are going to get me in hot water with GMG, GMG owners, and audiologists lurking on this forum.
But if you insist, how about this, roughly, very roughly, if stock Turbo is 1, stock 911 NA engine without sport exhaust is 2, with sport exhaust is 3, stock GT3 is 6-7, Porsche 911 race car up close is 10, then my Cargraphic is also about 6, the GMG would be 7-8, a mufflef-less GT3 I heard would be 9 (one of the best sound I ever heard, but I couldn't hear anything else for the next 30 minutes LOL). Your EP1 we know from many different sources to be not as loud as my Cargraphic, so we give it a 4-5. All very very rough estimates so everyone relax and hold the flaming.
Now that we have a "rating," I hope you could see why I have been so hesitant. Does my 8 rating mean GMG is "twice" as loud as the EP1 at 4? Well, what exactly is "twice as loud"? It's a subjective evaluation subjected to the individual listeners. Unless you have them next to each other and measured professionally, there is *no* way to tell.
The GMG is loud, but not prohibitively so, like that muffler-less GT3 that I heard. You could hear radio and you could hear people talk, just have to speak louder. Long trip with the wife is probably not a good idea though, but that's the job for the wife's car, not our Turbo baby.

If you are going to keep the car for 4 more years, and obviously you have the financial resource, I would say go for it. Pardon me if I am wrong but it seems you have quite an itch for the GMG. The things you are looking for in your various exhaust posts are exactly the things I found about the GMG. In particular, that deep rumble V8 sound. It sounds more American V8 than any other exhausts that I've heard and is indeed a beautiful and satisfying sound. Your EP1 should sell very quick on the secondary market, or keep it until you are absolutely sure the GMG fits your wish. I do not know how easy it is to sell GMG if you don't like it though. But what do the young people say nowadays - YOLO?

 

Cannga....thanks for 1-10 feedback on GMG. Can't go louder than EP1. Too loud an exhaust for street can often tear down some of the special GT/sports image designed in the Porsche turbo especially when used to occasionally transport wife, customers, etc.
Would be nice if GMG had different loudness-versions like Cargraphic, maybe something like that is in the works.
There are exhausts that provide both street and track in the same package, but my understanding is after some mileage and time, only then the louder version survives. Never really checked thoroughly with manufacturers to be sure this rumor was true.

 

To add a little to this discussion, we produce a quiet, sport, moderate and a loud X-Flow exhaust for the 997TT - all sound phenomenal. Our quiet version has no drone and sounds a lot like a 997 GT3. The loud is a full 3" system and due to our "internal X" muffler design, the drone is minimal for a full 3" system. Both are great choices for people looking for an exotic sound that is not over the top loud. We do offer a pure 3" X-Pipe for that very aggressive note, too - in fact it reminds me a lot of driving a Ferrari F430 - very unique and desirable sound for the 997TT!

On the 1-10 scale, 10 being straight out the back race pipes, I would say our quiet X-Flow muffler system is a 4-5 with no drone at all, sport is 5, moderate is 5.5 and our loud muffler system is a 6.5 and our straight 3" X-Pipe is an 8. Add 1 point to each level, if used with cat bypass pipes...

 

What about fvd compare to those u had posted?

 

Sorry I have not heard this or know any trustworthy ear who has. Would venture a guess from various postings that it's another medium sounding exhaust.

This should be a very good/excellent setup also. Owners seem very happy with the sound. I vaguely recall the first generation had a farting sound (not kidding) on deceleration or something to that effect (anyone pls correct me as needed), but this has been fixed to best of my knowledge. How much are these going for these days do you know?

 

Hi John, thanks for your input and good luck with your endeavor. I went to your web site and noticed you are using 100 cpsi cat and have a question please.

There is another after-market exhaust that uses 100 cpsi cat and although I am not sure, from description of another forum member I believe this exhaust has a built-in "bung extension" for the post cat sensor. I take this to mean maybe the 100 cpsi cat is not efficient enough and therefore this bung extender is needed (nothing wrong with this) to prevent Check Engine Light?? Am I correct and do you need to do same (built-in bung extender) with yours?

 

Hi Cannga,

Thanks. We use 200 cell cats on the 997TT...and we do incorporate a built in bung extender, as well, on the 997TT exhausts.