Performance Mods: Some general thoughts
#32
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Robin, 993RS: The 3.8L kit from Porsche includes a set of "sport" mufflers, perhaps they are specific to the RS? Or maybe just the motorsound mufflers? I guess Gert may be the best place to look for a definitive answer...
#33
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John,
Having had the chance to open a pair of those 3.8 power kit muffler myself I can tell you that contrary to what everyone thinks about that “sports” muffler that comes with the 3.8 kit it is even more restrictive than the standard 993 muffler.
Internally it is missing the by-pass tube that exists on the standard 993 mufflers, which makes them quieter.
I believe the reasoning for a quieter muffler with the 3.8 liter kit is because since the engine displacement is bumped up it is now producing more exhaust flow and more noise. So in order to meet the European drive by noise law Porsche had to make the muffler quieter in order for the car to meet the qualification and to be certified.
I believe Gert also had a chance in the past to open a 993 muffler that came off a Swiss 993, which was also missing the by-pass tube.
Below is a picture of the by-pass tube inside of a standard and motor sound 993 muffler.
Having had the chance to open a pair of those 3.8 power kit muffler myself I can tell you that contrary to what everyone thinks about that “sports” muffler that comes with the 3.8 kit it is even more restrictive than the standard 993 muffler.
Internally it is missing the by-pass tube that exists on the standard 993 mufflers, which makes them quieter.
I believe the reasoning for a quieter muffler with the 3.8 liter kit is because since the engine displacement is bumped up it is now producing more exhaust flow and more noise. So in order to meet the European drive by noise law Porsche had to make the muffler quieter in order for the car to meet the qualification and to be certified.
I believe Gert also had a chance in the past to open a 993 muffler that came off a Swiss 993, which was also missing the by-pass tube.
Below is a picture of the by-pass tube inside of a standard and motor sound 993 muffler.
![](http://p-car.com/exhaust/mufflercomparet.jpg)