Gutting a cat... with pics!
#32
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
![](https://forums.pelicanparts.com/uploads20/993_RSR_11340122316.jpg)
993Cup unmuffled
![](https://forums.pelicanparts.com/uploads20/993cup_header1340122696.jpg)
2007RSR
![](https://forums.pelicanparts.com/uploads20/2007_RSR_exhaust1340122535.gif)
2008RSR
![](https://forums.pelicanparts.com/uploads20/2008_RSR_11340122428.jpg)
2009 Cup unmuffled
![](https://forums.pelicanparts.com/uploads20/2009_Cup_unmuffled1340122635.gif)
2009 RSR
![](https://forums.pelicanparts.com/uploads20/2009_RSR_31340122754.jpg)
SC/RS
![](https://forums.pelicanparts.com/uploads20/SC+RS_11340122958.jpg)
964RS/lw
![](https://forums.pelicanparts.com/uploads20/porsche+964+c4+lwt+exhaust+sm1340123018.jpg)
![](https://forums.pelicanparts.com/uploads20/LWC4_5_16_04_+022+8+1340123055.jpg)
#33
Rennlist Member
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There are different ways to configure the exhaust
here is 1&2, 3&4 pairing
![](https://www.google.com/url?source=imglanding&ct=img&q=http://3.bp.blogspot.com/-dISMzIuFZFk/TgoB1hnnsMI/AAAAAAAAAvU/nQ-G0-OQOho/s1600/hdsai94gsrty1uo5.jpg&sa=X&ei=65zgT8KXKePi0QH5haS4Dg&ved=0CAwQ8wc&usg=AFQjCNGLw3DnkrSSVkdkba95reMudINLuQ)
here 1&3, 2&4 pairing
![](https://www.google.com/url?source=imglanding&ct=img&q=http://www.rageimports.com/images/imageupld/homepg/B%20SERIES%20HEADER.jpg&sa=X&ei=QZ3gT8f_C4rE0QHJpZmWDg&ved=0CAsQ8wc&usg=AFQjCNFr3woW5IvGePhHtvQr9-XV9KTYnQ)
here a 1&4, 2&3
![](https://www.google.com/url?source=imglanding&ct=img&q=http://www.cyclexchange.net/index%20pics/New%20Tri-Y%204.JPG&sa=X&ei=mJ3gT_SDPcX10gGvrvWBDg&ved=0CAwQ8wc&usg=AFQjCNGXVXZEfVurlufU1gbWYWnn9j-dsg)
Which you use depends on firing order and hoe you want to affect the torque curve
non sequential tri-y has the widest torque spread, 4 into 1 the narrowest but also the most peak hp, non sequential tri-y is in the middle
When I raced Honda MC we played around w/ this a lot, I see that current 4 cyl inline superbikes are also playing w/ crank variations to further alter the torque curves
here is 1&2, 3&4 pairing
![](https://www.google.com/url?source=imglanding&ct=img&q=http://3.bp.blogspot.com/-dISMzIuFZFk/TgoB1hnnsMI/AAAAAAAAAvU/nQ-G0-OQOho/s1600/hdsai94gsrty1uo5.jpg&sa=X&ei=65zgT8KXKePi0QH5haS4Dg&ved=0CAwQ8wc&usg=AFQjCNGLw3DnkrSSVkdkba95reMudINLuQ)
here 1&3, 2&4 pairing
![](https://www.google.com/url?source=imglanding&ct=img&q=http://www.rageimports.com/images/imageupld/homepg/B%20SERIES%20HEADER.jpg&sa=X&ei=QZ3gT8f_C4rE0QHJpZmWDg&ved=0CAsQ8wc&usg=AFQjCNFr3woW5IvGePhHtvQr9-XV9KTYnQ)
here a 1&4, 2&3
Which you use depends on firing order and hoe you want to affect the torque curve
non sequential tri-y has the widest torque spread, 4 into 1 the narrowest but also the most peak hp, non sequential tri-y is in the middle
When I raced Honda MC we played around w/ this a lot, I see that current 4 cyl inline superbikes are also playing w/ crank variations to further alter the torque curves
Any dyno results for the *** setup?
#34
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1-3 paired , 4-2 paired gives B--B--S--S to each primary pair, I added the extra - because the cyl fire every 180* instead of the 90* in a V8
so this one
![](https://www.google.com/url?source=imglanding&ct=img&q=http://www.rageimports.com/images/imageupld/homepg/B%20SERIES%20HEADER.jpg&sa=X&ei=QZ3gT8f_C4rE0QHJpZmWDg&ved=0CAsQ8wc&usg=AFQjCNFr3woW5IvGePhHtvQr9-XV9KTYnQ)
#35
Rennlist Member
#36
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
I visited the manufacturer of Dansk Mufflers for our cars.
They are located in Viborg, Denmark and are called JP Group a/s.
The company makes mufflers, headers, catalytic converters, etc. for Porsche to a very high standard in stainless steel.
I found the company to be much larger than I expected with a 270,000 square foot facility that not only makes exhaust for Porsche but other makes as well.
They also are a distributing manufacturer for many other chassis parts and body panels.
The owner appears to be a Porsche freak and has a showroom with his collection of cars, mostly Porsche's, which I visited along with the manufacturing facility.
He drives a 991 Convertible and a Panamera.
The front door of JP Group a/s
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16129-jp-group-2012-1-no-preben.jpg)
Inside in a high security area is the entrance to their "showroom" with various cars collected and a show area for all the other parts that JP makes
for suspension, lighting, etc. besides just exhaust which are shown in the glass cases in the background.
A familiar shape done in fiberglass is over the door to the showroom
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16135-jp-group-2012-3.jpg)
Inside is an immaculate collection that includes many Porsche's plus things like the 10th from last VW Beatle ever made which has only 700 km on the odometer.
[IMG]
[/IMG]
This is the Dansk 993 header system with 100 cell Cats and mufflers.
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16131-jp-group-2012-8.jpg)
The pipes to the right are Bischoff 993 Cat bypass pipes, in the center is a 964 primary muffler bypass.
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16139-jp-group-2012-9.jpg)
Examples of early 911 Dansk mufflers both in stock and "Motorsport" versions
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16138-jp-group-2012-10.jpg)
993 Bischoff OE heat exchanger pipes in process of fabrication.
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16136-jp-group-2012-16.jpg)
Stainless covers for early 911 heat exchanger.
They are located in Viborg, Denmark and are called JP Group a/s.
The company makes mufflers, headers, catalytic converters, etc. for Porsche to a very high standard in stainless steel.
I found the company to be much larger than I expected with a 270,000 square foot facility that not only makes exhaust for Porsche but other makes as well.
They also are a distributing manufacturer for many other chassis parts and body panels.
The owner appears to be a Porsche freak and has a showroom with his collection of cars, mostly Porsche's, which I visited along with the manufacturing facility.
He drives a 991 Convertible and a Panamera.
The front door of JP Group a/s
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16129-jp-group-2012-1-no-preben.jpg)
Inside in a high security area is the entrance to their "showroom" with various cars collected and a show area for all the other parts that JP makes
for suspension, lighting, etc. besides just exhaust which are shown in the glass cases in the background.
A familiar shape done in fiberglass is over the door to the showroom
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16135-jp-group-2012-3.jpg)
Inside is an immaculate collection that includes many Porsche's plus things like the 10th from last VW Beatle ever made which has only 700 km on the odometer.
[IMG]
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16130-jp-group-2012-4.jpg)
This is the Dansk 993 header system with 100 cell Cats and mufflers.
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16131-jp-group-2012-8.jpg)
The pipes to the right are Bischoff 993 Cat bypass pipes, in the center is a 964 primary muffler bypass.
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16139-jp-group-2012-9.jpg)
Examples of early 911 Dansk mufflers both in stock and "Motorsport" versions
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16138-jp-group-2012-10.jpg)
993 Bischoff OE heat exchanger pipes in process of fabrication.
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16136-jp-group-2012-16.jpg)
Stainless covers for early 911 heat exchanger.
![](https://rennlist.com/forums/members/cupcar-albums-dansk-picture16137-jp-group-2012-17.jpg)
#38
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
So to conclude (and correct me if I am wrong)
1. A true X pipe has not been proven to make btter sound, HP or Torque.
2. Cat bypass will lower torque a bit but is louder.
3. Nobody currently makes a "u bend" cat bypass that follows the route of the stock airflow and retains most the backpressure/torque without the use of any cats but still has the bungs for O2 sensors.
4. If someone were to develop such a thing, there maight be interet from others in buying such a thing as long as it is bolt on with no welding, stainless and affordable...say under $500.
1. A true X pipe has not been proven to make btter sound, HP or Torque.
2. Cat bypass will lower torque a bit but is louder.
3. Nobody currently makes a "u bend" cat bypass that follows the route of the stock airflow and retains most the backpressure/torque without the use of any cats but still has the bungs for O2 sensors.
4. If someone were to develop such a thing, there maight be interet from others in buying such a thing as long as it is bolt on with no welding, stainless and affordable...say under $500.