Aftermarket exhaust advice
04-20-2022, 11:18 PM
#1
Advanced
Thread Starter
Aftermarket exhaust advice
I have a 2007 GT3 with a center muffler bypass from RSS. I’ve been thinking of deleting the side mufflers. I have a few questions:
1) if I use side muffler bypass pipes, is there any reason to purchase a bypass with helical valves if I have already deleted the center muffler? Is the valve needed to produce back pressure?
2) is there any advantage to the combination of a side muffler bypass pipes and a center muffler bypass over just running straight pipes out from the catalytic converters (fab speed has an x-pipe which accomplishes this).
3) do muffler bypass pipes, combined with the fabspeed center muffler bypass, which has a resonance tube which is supposed to prevent horsepower losses, have any advantage over keeping the RSS center muffler bypass pipe or doing the x-pipe?
When I first got the car, a couple years ago, it came with the center bypass installed, but had faulty helical valves, so it sounded really loud and raw, like a 1970’s race car. I thought it was a little too much, so I tried installing the factory muffler to quiet it down a bit, but that caused an insufferable drone, and I eventually figured out that the valves were the problem. As soon as I installed replacement valves, the drone went away but the car quieted down way too much and I immediately reinstalled the center muffler bypass. While this has been fine for daily driving, I now miss the loud 1970s race car sounding exhaust note. I also can’t tell any difference between the sport and non-sport settings on the current setup in terms of noise and I want to have something a little more aggressive. Right now it sounds too much like any 911. I’d like people to hear it coming and know that it is a GT3. I live in miami, so folks aren’t prudish about sound levels.
Performance gains are also important to me; spending money to lose performance seems like a silly idea, but I understand that it is easy to do with GT3s. Someone was telling me that I would significantly reduce low end torque if I didn’t pick the right system. Since the car is street driven much more than track driven, I’d prefer to preserve low end torque if one setup favors that over another. Of course, if the differences are all too small to notice, then I suppose it doesn’t really matter as much as having a car that is exhilarating to drive. We all know that the right exhaust note can contribute a lot to that.
The car currently has a bmc air filter and it was chipped/mapped by EVO Motorsports by the previous owner (an invoice that came with the car says it got the “heel and toe” throttle mapping, which I find very enjoyable).
Let me know what you think is the best option.
1) if I use side muffler bypass pipes, is there any reason to purchase a bypass with helical valves if I have already deleted the center muffler? Is the valve needed to produce back pressure?
2) is there any advantage to the combination of a side muffler bypass pipes and a center muffler bypass over just running straight pipes out from the catalytic converters (fab speed has an x-pipe which accomplishes this).
3) do muffler bypass pipes, combined with the fabspeed center muffler bypass, which has a resonance tube which is supposed to prevent horsepower losses, have any advantage over keeping the RSS center muffler bypass pipe or doing the x-pipe?
When I first got the car, a couple years ago, it came with the center bypass installed, but had faulty helical valves, so it sounded really loud and raw, like a 1970’s race car. I thought it was a little too much, so I tried installing the factory muffler to quiet it down a bit, but that caused an insufferable drone, and I eventually figured out that the valves were the problem. As soon as I installed replacement valves, the drone went away but the car quieted down way too much and I immediately reinstalled the center muffler bypass. While this has been fine for daily driving, I now miss the loud 1970s race car sounding exhaust note. I also can’t tell any difference between the sport and non-sport settings on the current setup in terms of noise and I want to have something a little more aggressive. Right now it sounds too much like any 911. I’d like people to hear it coming and know that it is a GT3. I live in miami, so folks aren’t prudish about sound levels.
Performance gains are also important to me; spending money to lose performance seems like a silly idea, but I understand that it is easy to do with GT3s. Someone was telling me that I would significantly reduce low end torque if I didn’t pick the right system. Since the car is street driven much more than track driven, I’d prefer to preserve low end torque if one setup favors that over another. Of course, if the differences are all too small to notice, then I suppose it doesn’t really matter as much as having a car that is exhilarating to drive. We all know that the right exhaust note can contribute a lot to that.
The car currently has a bmc air filter and it was chipped/mapped by EVO Motorsports by the previous owner (an invoice that came with the car says it got the “heel and toe” throttle mapping, which I find very enjoyable).
Let me know what you think is the best option.
04-21-2022, 12:29 AM
#2
Rennlist Member
I have the sharkwerks competition exhaust. Basically, Catback with no mufflers. I love the sound it makes. I also live in Miami. We can get together so you can hear it.
04-21-2022, 06:20 PM
#3
Rennlist Member
regarding your question #1 - I think the "reason" many guys go with a side bypass that includes the valves, is because they are "trying" to maintain some sort of quieter mode when the valves are closed. I don't think it is to preserve some level of back pressure (as you stated).
The feedback we seem to hear most frequently about having side muffler delete WITH valves,... is that re-routing the exhaust gases (even if just a small upward re-route through a smaller tube diameter) only reduces the loudness by a very small amount. Once the guys who have done that, and experienced it for a length of time, seem to eventually say that it was not worth including the valves. If you want it loud, run it straight out the back (like you said with the Fabspeed option).
I have often thought I would like mine louder (but only WHEN I WANT it louder,... which is usually only once I am deep into those back roads & by myself)... but I already have the SW center bypass. Sure I'd love to shave 40 lbs off the back end by deleting my side mufflers,... but I have just not yet heard of a good setup that gives me VERY quiet operation when valves closed, and VERY loud when open.
your questions #2 & 3 look like they should be answered by the aftermarket exhaust manufacturers
The feedback we seem to hear most frequently about having side muffler delete WITH valves,... is that re-routing the exhaust gases (even if just a small upward re-route through a smaller tube diameter) only reduces the loudness by a very small amount. Once the guys who have done that, and experienced it for a length of time, seem to eventually say that it was not worth including the valves. If you want it loud, run it straight out the back (like you said with the Fabspeed option).
I have often thought I would like mine louder (but only WHEN I WANT it louder,... which is usually only once I am deep into those back roads & by myself)... but I already have the SW center bypass. Sure I'd love to shave 40 lbs off the back end by deleting my side mufflers,... but I have just not yet heard of a good setup that gives me VERY quiet operation when valves closed, and VERY loud when open.
your questions #2 & 3 look like they should be answered by the aftermarket exhaust manufacturers
Last edited by bweSteve; 04-21-2022 at 06:21 PM.
04-21-2022, 08:10 PM
#4
Advanced
Thread Starter
04-21-2022, 08:13 PM
#5
Advanced
Thread Starter
regarding your question #1 - I think the "reason" many guys go with a side bypass that includes the valves, is because they are "trying" to maintain some sort of quieter mode when the valves are closed. I don't think it is to preserve some level of back pressure (as you stated).
The feedback we seem to hear most frequently about having side muffler delete WITH valves,... is that re-routing the exhaust gases (even if just a small upward re-route through a smaller tube diameter) only reduces the loudness by a very small amount. Once the guys who have done that, and experienced it for a length of time, seem to eventually say that it was not worth including the valves. If you want it loud, run it straight out the back (like you said with the Fabspeed option).
I have often thought I would like mine louder (but only WHEN I WANT it louder,... which is usually only once I am deep into those back roads & by myself)... but I already have the SW center bypass. Sure I'd love to shave 40 lbs off the back end by deleting my side mufflers,... but I have just not yet heard of a good setup that gives me VERY quiet operation when valves closed, and VERY loud when open.
your questions #2 & 3 look like they should be answered by the aftermarket exhaust manufacturers
The feedback we seem to hear most frequently about having side muffler delete WITH valves,... is that re-routing the exhaust gases (even if just a small upward re-route through a smaller tube diameter) only reduces the loudness by a very small amount. Once the guys who have done that, and experienced it for a length of time, seem to eventually say that it was not worth including the valves. If you want it loud, run it straight out the back (like you said with the Fabspeed option).
I have often thought I would like mine louder (but only WHEN I WANT it louder,... which is usually only once I am deep into those back roads & by myself)... but I already have the SW center bypass. Sure I'd love to shave 40 lbs off the back end by deleting my side mufflers,... but I have just not yet heard of a good setup that gives me VERY quiet operation when valves closed, and VERY loud when open.
your questions #2 & 3 look like they should be answered by the aftermarket exhaust manufacturers
04-21-2022, 08:25 PM
#6
Rennlist Member
Originally Posted by bweSteve
regarding your question #1 - I think the "reason" many guys go with a side bypass that includes the valves, is because they are "trying" to maintain some sort of quieter mode when the valves are closed. I don't think it is to preserve some level of back pressure (as you stated).
The feedback we seem to hear most frequently about having side muffler delete WITH valves,... is that re-routing the exhaust gases (even if just a small upward re-route through a smaller tube diameter) only reduces the loudness by a very small amount. Once the guys who have done that, and experienced it for a length of time, seem to eventually say that it was not worth including the valves. If you want it loud, run it straight out the back (like you said with the Fabspeed option).
I have often thought I would like mine louder (but only WHEN I WANT it louder,... which is usually only once I am deep into those back roads & by myself)... but I already have the SW center bypass. Sure I'd love to shave 40 lbs off the back end by deleting my side mufflers,... but I have just not yet heard of a good setup that gives me VERY quiet operation when valves closed, and VERY loud when open.
your questions #2 & 3 look like they should be answered by the aftermarket exhaust manufacturers
The feedback we seem to hear most frequently about having side muffler delete WITH valves,... is that re-routing the exhaust gases (even if just a small upward re-route through a smaller tube diameter) only reduces the loudness by a very small amount. Once the guys who have done that, and experienced it for a length of time, seem to eventually say that it was not worth including the valves. If you want it loud, run it straight out the back (like you said with the Fabspeed option).
I have often thought I would like mine louder (but only WHEN I WANT it louder,... which is usually only once I am deep into those back roads & by myself)... but I already have the SW center bypass. Sure I'd love to shave 40 lbs off the back end by deleting my side mufflers,... but I have just not yet heard of a good setup that gives me VERY quiet operation when valves closed, and VERY loud when open.
your questions #2 & 3 look like they should be answered by the aftermarket exhaust manufacturers
04-21-2022, 09:09 PM
#7
Rennlist Member
I have a 2007 GT3 with a center muffler bypass from RSS. I’ve been thinking of deleting the side mufflers. I have a few questions:
1) if I use side muffler bypass pipes, is there any reason to purchase a bypass with helical valves if I have already deleted the center muffler? Is the valve needed to produce back pressure?
2) is there any advantage to the combination of a side muffler bypass pipes and a center muffler bypass over just running straight pipes out from the catalytic converters (fab speed has an x-pipe which accomplishes this).
3) do muffler bypass pipes, combined with the fabspeed center muffler bypass, which has a resonance tube which is supposed to prevent horsepower losses, have any advantage over keeping the RSS center muffler bypass pipe or doing the x-pipe?
When I first got the car, a couple years ago, it came with the center bypass installed, but had faulty helical valves, so it sounded really loud and raw, like a 1970’s race car. I thought it was a little too much, so I tried installing the factory muffler to quiet it down a bit, but that caused an insufferable drone, and I eventually figured out that the valves were the problem. As soon as I installed replacement valves, the drone went away but the car quieted down way too much and I immediately reinstalled the center muffler bypass. While this has been fine for daily driving, I now miss the loud 1970s race car sounding exhaust note. I also can’t tell any difference between the sport and non-sport settings on the current setup in terms of noise and I want to have something a little more aggressive. Right now it sounds too much like any 911. I’d like people to hear it coming and know that it is a GT3. I live in miami, so folks aren’t prudish about sound levels.
Performance gains are also important to me; spending money to lose performance seems like a silly idea, but I understand that it is easy to do with GT3s. Someone was telling me that I would significantly reduce low end torque if I didn’t pick the right system. Since the car is street driven much more than track driven, I’d prefer to preserve low end torque if one setup favors that over another. Of course, if the differences are all too small to notice, then I suppose it doesn’t really matter as much as having a car that is exhilarating to drive. We all know that the right exhaust note can contribute a lot to that.
The car currently has a bmc air filter and it was chipped/mapped by EVO Motorsports by the previous owner (an invoice that came with the car says it got the “heel and toe” throttle mapping, which I find very enjoyable).
Let me know what you think is the best option.
1) if I use side muffler bypass pipes, is there any reason to purchase a bypass with helical valves if I have already deleted the center muffler? Is the valve needed to produce back pressure?
2) is there any advantage to the combination of a side muffler bypass pipes and a center muffler bypass over just running straight pipes out from the catalytic converters (fab speed has an x-pipe which accomplishes this).
3) do muffler bypass pipes, combined with the fabspeed center muffler bypass, which has a resonance tube which is supposed to prevent horsepower losses, have any advantage over keeping the RSS center muffler bypass pipe or doing the x-pipe?
When I first got the car, a couple years ago, it came with the center bypass installed, but had faulty helical valves, so it sounded really loud and raw, like a 1970’s race car. I thought it was a little too much, so I tried installing the factory muffler to quiet it down a bit, but that caused an insufferable drone, and I eventually figured out that the valves were the problem. As soon as I installed replacement valves, the drone went away but the car quieted down way too much and I immediately reinstalled the center muffler bypass. While this has been fine for daily driving, I now miss the loud 1970s race car sounding exhaust note. I also can’t tell any difference between the sport and non-sport settings on the current setup in terms of noise and I want to have something a little more aggressive. Right now it sounds too much like any 911. I’d like people to hear it coming and know that it is a GT3. I live in miami, so folks aren’t prudish about sound levels.
Performance gains are also important to me; spending money to lose performance seems like a silly idea, but I understand that it is easy to do with GT3s. Someone was telling me that I would significantly reduce low end torque if I didn’t pick the right system. Since the car is street driven much more than track driven, I’d prefer to preserve low end torque if one setup favors that over another. Of course, if the differences are all too small to notice, then I suppose it doesn’t really matter as much as having a car that is exhilarating to drive. We all know that the right exhaust note can contribute a lot to that.
The car currently has a bmc air filter and it was chipped/mapped by EVO Motorsports by the previous owner (an invoice that came with the car says it got the “heel and toe” throttle mapping, which I find very enjoyable).
Let me know what you think is the best option.
If you're looking for sound gains, then you have a lot of options.
I've run fully stock, stock with RSS center delete, stock with Sharkwerks center delete and a full system with long tube headers. If you have the Evoms tune, get yourself a set of long tube headers from Dundon or Brombacher and your car will pull like a freight train.
No other combination of mufflers alone is going to net your anything worthwhile. In fact, I felt a power loss with my center delete pipes I ran. My stock system felt faster than both the RSS and Sharkwerks center deletes, but the sound on both was amazing. I liked the RSS sound a wee bit better.
Last edited by RAudi Driver; 04-26-2022 at 12:41 PM.
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04-26-2022, 11:10 AM
#8
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If you're looking for performance gains, side deletes will help from a weight perspective which you will feel. Power changes from muffler replacements are relatively negligible. If you want a tangible power increase you'll want to look into headers and software, as that's where you'll feel the difference. Side and center deletes combined will be a bit more reasonable at cruising speeds due to having a secondary flow path in action which can help take the edge off the resonance, and also serves to smooth out the tone a bit vs have a straight pipe from headers to tips. Feel free to give me a ring anytime, I'm always happy to chat cars and go in depth on various setups to help make an educated decision with realistic expectations.
Regards,
John Gaydos
Regards,
John Gaydos
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jwheel@soulpp.com
SOUL PERFORMANCE PRODUCTS
Quality Exhaust Solutions, Fair Pricing, and Outstanding Service
John Gaydos- Owner, Performance Specialist
Cell - (484) 883-6197
johng@soulpp.com
Jon Wheel - Marketing Manager
jwheel@soulpp.com
04-26-2022, 02:53 PM
#9
Back pressure isn't anything you want or need. Its a fallacy.
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Jamie@dundonmotorsports (05-30-2022)
04-27-2022, 08:22 AM
#10
Nordschleife Master
I put a Sharkwerks center bypass on. Didn’t notice any power difference but sure noticed a sound difference with valves open. Sounds great.
I am amazed at trying to save 40lbs in the rear with side deletes. I can’t image anyone being able to honestly say they noticed a difference on a street driven car. If you want them for more power and sound especially with headers ok then I get it.
The RS is more than fast enough stock and has ability that can’t be fully tap on the street safely out of the box. To me if you want faster in a straight line get a C7 ZO6.
I am amazed at trying to save 40lbs in the rear with side deletes. I can’t image anyone being able to honestly say they noticed a difference on a street driven car. If you want them for more power and sound especially with headers ok then I get it.
The RS is more than fast enough stock and has ability that can’t be fully tap on the street safely out of the box. To me if you want faster in a straight line get a C7 ZO6.
Last edited by Waxer; 04-27-2022 at 08:28 AM.
05-01-2022, 09:24 PM
#11
Intermediate
05-02-2022, 01:10 PM
#12
Back pressure... Hmmmm. I've heard different perspectives. There are those that swear that back pressure is important. I know that's the way they came from the factory, and I trust Porsche on that front. Thoughts on the "no need to worry about back pressure", therefore side muffler delete is ok? TIA
05-03-2022, 01:40 PM
#13
Back pressure... Hmmmm. I've heard different perspectives. There are those that swear that back pressure is important. I know that's the way they came from the factory, and I trust Porsche on that front. Thoughts on the "no need to worry about back pressure", therefore side muffler delete is ok? TIA
05-03-2022, 03:14 PM
#14
Rennlist Member
I totally get where Burren is coming from but you can't really talk about back pressure without including velocity and scavenging. Both play a major role in producing power. Back pressure isn't good but take it all away and you
you'll have a car that doesn't run well unless it's flat out. I think a properly engineered exhaust system is the best for usable power for the common folks.
All I now is that my stock 997.1 ran better with the stock system on it then a center delete, or the full Brombacher system, with no tune. I threw the Brombacher system on my Evoms tuned .1RS and holy cow, man does it pull hard.
you'll have a car that doesn't run well unless it's flat out. I think a properly engineered exhaust system is the best for usable power for the common folks.
All I now is that my stock 997.1 ran better with the stock system on it then a center delete, or the full Brombacher system, with no tune. I threw the Brombacher system on my Evoms tuned .1RS and holy cow, man does it pull hard.
