Best Exhaust for a 991.2 GT3
06-24-2018, 03:00 PM
#601
Rennlist Member
Incorrect! A member here dyno’ed the exhaust with the valve connected/disconnected.
Here are the results: https://rennlist.com/forums/991-gt3-...st-valves.html
Here are the results: https://rennlist.com/forums/991-gt3-...st-valves.html
06-24-2018, 03:03 PM
#602
Burning Brakes
I put a SW center delete on my .1 GT3 first and didn’t think it did anything to the sound below 4000 rpm and I had already “forced” the valves open all the time. I wanted the car to sound better so I put on FVD side deletes which dropped many pounds in weight, removed the large heat sink right by rear tires and also improved sound quality imo. I reinstalled the OEM center bypass with the side deletes but with my incoming I think I might remove all of them. I need to look at a few of the newer systems. That said if you really want sound the biggest bang for the buck is to remove or replace the cats with 200 cel race ones. Then there’s a significant dB jump.
06-24-2018, 10:40 PM
#603
RL Community Team
Rennlist Member
Rennlist Member
Incorrect! A member here dyno’ed the exhaust with the valve connected/disconnected.
Here are the results: https://rennlist.com/forums/991-gt3-...st-valves.html
06-25-2018, 12:58 AM
#604
Basic Sponsor
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Just a few observations form what we have seen over the years....
-installing side deletes definitely increases the sound limits, in most cases, making it extremely loud. If that's what you want, a great option but be prepared for a hearing aide in your near future.
-Center deletes, at least ours, makes the most dramatic sound increase while maintaining the usability of the stock valves and maintaining the continuity of the OEM system.
-Our system is full compatible and modular with side deletes and headers, as we have sold each individually, or all 3 together.
-Removing weight in the back of the car is always nice but unless you are really tracking the car more often than not, you probably won't feel the difference.
-Center Sections seem to be the most popular because the sound increase is fairly dramatic but without the drone of side deletes or potential check engine lights with catless headers.
-installing side deletes definitely increases the sound limits, in most cases, making it extremely loud. If that's what you want, a great option but be prepared for a hearing aide in your near future.
-Center deletes, at least ours, makes the most dramatic sound increase while maintaining the usability of the stock valves and maintaining the continuity of the OEM system.
-Our system is full compatible and modular with side deletes and headers, as we have sold each individually, or all 3 together.
-Removing weight in the back of the car is always nice but unless you are really tracking the car more often than not, you probably won't feel the difference.
-Center Sections seem to be the most popular because the sound increase is fairly dramatic but without the drone of side deletes or potential check engine lights with catless headers.
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James F. Sofronas | President & Owner
Global Motorsports Group ™
E: james@gmgracing.com
P: +1 (714) 432-1582
F: +1 (714) 432-1590
A: 3210 South Shannon Street, Santa Ana, California 92704
W: gmgracing.com
06-25-2018, 02:28 AM
#605
Just a few observations form what we have seen over the years....
-installing side deletes definitely increases the sound limits, in most cases, making it extremely loud. If that's what you want, a great option but be prepared for a hearing aide in your near future.
-Center deletes, at least ours, makes the most dramatic sound increase while maintaining the usability of the stock valves and maintaining the continuity of the OEM system.
-Our system is full compatible and modular with side deletes and headers, as we have sold each individually, or all 3 together.
-Removing weight in the back of the car is always nice but unless you are really tracking the car more often than not, you probably won't feel the difference.
-Center Sections seem to be the most popular because the sound increase is fairly dramatic but without the drone of side deletes or potential check engine lights with catless headers.
-installing side deletes definitely increases the sound limits, in most cases, making it extremely loud. If that's what you want, a great option but be prepared for a hearing aide in your near future.
-Center deletes, at least ours, makes the most dramatic sound increase while maintaining the usability of the stock valves and maintaining the continuity of the OEM system.
-Our system is full compatible and modular with side deletes and headers, as we have sold each individually, or all 3 together.
-Removing weight in the back of the car is always nice but unless you are really tracking the car more often than not, you probably won't feel the difference.
-Center Sections seem to be the most popular because the sound increase is fairly dramatic but without the drone of side deletes or potential check engine lights with catless headers.
06-25-2018, 05:25 AM
#606
My personal observation with the center muffler delete on a .2 manual:
It is indeed louder without being too loud and still gives the opportunity to come home quietly. No drone also and
mainly outside racecar-like at WOT. Rev matching is also finally really sharp.
But, there´s one big but, and maybe it´s just me: the sound quality is not enhanced, it actually looses character and
typical flat six notes.
Two examples, compared to stock with blocked exhaust valves:
-below 4000rpm, there is a nice tone/growl that reminds me of the air cooled era. Very Porsche and distinctive.
With cmd-> gone, replaced by louder and unspecific noise
-above 7500rpm, when the induction noise takes over and makes your eyes water, reminds you of e30 m3´s in the early 90s.
With cmd->gone, just loud, so loud the induction noise is no longer heard
Trouble is, even though I really love the stock sound, I´d like it louder, sharper, but without loosing the lovely tones.
How did you guys with side muffler delete experience this?
Peter
It is indeed louder without being too loud and still gives the opportunity to come home quietly. No drone also and
mainly outside racecar-like at WOT. Rev matching is also finally really sharp.
But, there´s one big but, and maybe it´s just me: the sound quality is not enhanced, it actually looses character and
typical flat six notes.
Two examples, compared to stock with blocked exhaust valves:
-below 4000rpm, there is a nice tone/growl that reminds me of the air cooled era. Very Porsche and distinctive.
With cmd-> gone, replaced by louder and unspecific noise
-above 7500rpm, when the induction noise takes over and makes your eyes water, reminds you of e30 m3´s in the early 90s.
With cmd->gone, just loud, so loud the induction noise is no longer heard
Trouble is, even though I really love the stock sound, I´d like it louder, sharper, but without loosing the lovely tones.
How did you guys with side muffler delete experience this?
Peter
06-25-2018, 04:41 PM
#607
Former Vendor
I heard that side deletes will give you a moderate increase in noise (less variance between valves open and closed as gas etc passes through center muffler) and slightly different tone, whereas center bypass will give you a more pronounced difference between valves open and closed with overall a larger increase in noise
John @ AutoQuest told me this, I appreciate him taking the time to talk and walk me through the exhaust options over the phone as an interested bystander (have ZERO experience with either FWIW)
John @ AutoQuest told me this, I appreciate him taking the time to talk and walk me through the exhaust options over the phone as an interested bystander (have ZERO experience with either FWIW)
To add to this, *Valved* side muffler bypass pipes are key to note here. Without them being valved, they are essentially in the valves-open position at all times and can have more of a cabin presence. Non-Valved side muffler bypass pipes will tend have more cabin presence at cruising speed than a center muffler bypass pipe with valves closed.
I believe the loss of torque is when the valves are no longer present. I believe the valves create back pressure.
Valve delete, I believe so. I also believe, after speaking with John (who is awesome by the way) that on a Center muffler delete, most valved systems when closed route the air tona dofferent section of the Center Muffler which isn’t their on an Center bypass. I could have misunderstood this point, but I don’t believe so.
It was my understanding side delete isn’t as loud as centre bypass. Can you confirm please?
Can you expand on why you feel side delete sounds better? I was under the impression center bypass sounds louder and better.
Valve delete, I believe so. I also believe, after speaking with John (who is awesome by the way) that on a Center muffler delete, most valved systems when closed route the air tona dofferent section of the Center Muffler which isn’t their on an Center bypass. I could have misunderstood this point, but I don’t believe so.
It was my understanding side delete isn’t as loud as centre bypass. Can you confirm please?
Can you expand on why you feel side delete sounds better? I was under the impression center bypass sounds louder and better.
You are correct by the way. In either a Valved Side Muffler Bypass or Center Muffler Bypass, with valves closed there is more backpressure than in the valves open position. With the Valved Side Muffler Bypass, exhaust is routed through the more restrictive upper area of the center muffler. With a Center Muffler Bypass, exhaust is routed through a more restrictive area of the side mufflers. In both setups, valves closed is more restrictive and offers some backpressure to offset low end torque loss before the valves open automatically.
My personal observation with the center muffler delete on a .2 manual:
It is indeed louder without being too loud and still gives the opportunity to come home quietly. No drone also and
mainly outside racecar-like at WOT. Rev matching is also finally really sharp.
But, there´s one big but, and maybe it´s just me: the sound quality is not enhanced, it actually looses character and
typical flat six notes.
Two examples, compared to stock with blocked exhaust valves:
-below 4000rpm, there is a nice tone/growl that reminds me of the air cooled era. Very Porsche and distinctive.
With cmd-> gone, replaced by louder and unspecific noise
-above 7500rpm, when the induction noise takes over and makes your eyes water, reminds you of e30 m3´s in the early 90s.
With cmd->gone, just loud, so loud the induction noise is no longer heard
Trouble is, even though I really love the stock sound, I´d like it louder, sharper, but without loosing the lovely tones.
How did you guys with side muffler delete experience this?
Peter
It is indeed louder without being too loud and still gives the opportunity to come home quietly. No drone also and
mainly outside racecar-like at WOT. Rev matching is also finally really sharp.
But, there´s one big but, and maybe it´s just me: the sound quality is not enhanced, it actually looses character and
typical flat six notes.
Two examples, compared to stock with blocked exhaust valves:
-below 4000rpm, there is a nice tone/growl that reminds me of the air cooled era. Very Porsche and distinctive.
With cmd-> gone, replaced by louder and unspecific noise
-above 7500rpm, when the induction noise takes over and makes your eyes water, reminds you of e30 m3´s in the early 90s.
With cmd->gone, just loud, so loud the induction noise is no longer heard
Trouble is, even though I really love the stock sound, I´d like it louder, sharper, but without loosing the lovely tones.
How did you guys with side muffler delete experience this?
Peter
06-25-2018, 04:43 PM
#608
Basic Sponsor
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For the most part, both, as we get a lot of cars through this shop and I always take the time to hear each and everyone of them, whether they have our products on them or a competitor.
06-28-2018, 10:23 AM
#610
Rennlist Member
An important factor that warrants discussion is the aggressiveness of the exhaust note from inside the car vs. how it sounds to someone standing behind the car. The two are definitely not always the same. For me, the perfect exhaust setup can address both. I have a center muffler delete on my current touring, and it sounds incredible from the outside...but I must say that I'm leaning toward getting a full new exhaust system because I'm searching for a better note on the inside. On my 991.1 GT3, the side muffler delete was an excellent compromise that to my ears sounded great both inside and outside.
06-28-2018, 12:03 PM
#611
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They are not compatible. The Dual 4 inch tips are too large for the bumpers exhaust opening.
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06-28-2018, 03:26 PM
#613
Three Wheelin'
Thread Starter
An important factor that warrants discussion is the aggressiveness of the exhaust note from inside the car vs. how it sounds to someone standing behind the car. The two are definitely not always the same. For me, the perfect exhaust setup can address both. I have a center muffler delete on my current touring, and it sounds incredible from the outside...but I must say that I'm leaning toward getting a full new exhaust system because I'm searching for a better note on the inside. On my 991.1 GT3, the side muffler delete was an excellent compromise that to my ears sounded great both inside and outside.
06-28-2018, 04:01 PM
#614
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An important factor that warrants discussion is the aggressiveness of the exhaust note from inside the car vs. how it sounds to someone standing behind the car. The two are definitely not always the same. For me, the perfect exhaust setup can address both. I have a center muffler delete on my current touring, and it sounds incredible from the outside...but I must say that I'm leaning toward getting a full new exhaust system because I'm searching for a better note on the inside. On my 991.1 GT3, the side muffler delete was an excellent compromise that to my ears sounded great both inside and outside.
06-28-2018, 04:02 PM
#615
An important factor that warrants discussion is the aggressiveness of the exhaust note from inside the car vs. how it sounds to someone standing behind the car. The two are definitely not always the same. For me, the perfect exhaust setup can address both. I have a center muffler delete on my current touring, and it sounds incredible from the outside...but I must say that I'm leaning toward getting a full new exhaust system because I'm searching for a better note on the inside. On my 991.1 GT3, the side muffler delete was an excellent compromise that to my ears sounded great both inside and outside.