Would there be any advange to using a 2003 Porsche GT2 exhaust on a 2001 996 TT? What are the differences in the stock exhaust systems?

Ryan

 

Same.

 

Are the factory headers the same?

 

all the same. I heard the GT2 IC's are a realistic 2-4% improvement

 

I was told by TPC that the GT2 and X50 exhausts were not the same as the regular turbo and were superior to the regular turbo exhausts.

 

X50 and GT2 exhausts are the same..... stock tt muffler is different but not worth to change it....(GT2/X50 have a greater holes inside the muffler but same cats...no real improvement) headers are the same on GT2/X50 and stock TT

 

I guess the big question is, how good are the factory cats. Can they be used as part of a free flowing exhaust or are they so restrictive that it is not worth it. Does anyone know if they are 200,300,400 etc cel cats?

 

the factory cats are 400.....two cats on every side....this cats are a great restriction imho

 

two cats on each side? My factory exhaust only has one on each side. There is barely enough room for one much less two on one side. so each individual unit is 400 cel then?

 

every factory muffler have two cats on every side...first cat direct after the turbos...second cat after the second oxygensensor...if you remove the second oxygensensor you can see a great diameter second cat ....heavy and great...if you remove this two cats and use one 100cell on every side on a factory muffler you have a improvement...but work and material cost a lot and the better way is a aftermarket muffler for my understanding

The oem cats are restrictive

 

interesting. I never noticed that. I will look at my factory exhaust tonight.

 

Yep 2 cats. A 200 then a 400 cat I believe then the open area that the tube you see out the back snakes through. Look up the thread about the TJW mod I believe it is called. It has a great cut away pic of a stock oem muffler

 

The stock 996 TT / X50 / GT2 cats are 300 cpsi not 400 cpsi.
cpsi = cells per square inch
So with the 300 cpsi cats there are about 17.5 cells per inch.
17.5 cells / inch x 17.5 cells / inch = 306 cells per square inch.

The stock cats of the 964 , 993 Carrera , 993 Turbo , 996 Carrera , 996 GT3 all have 300 cpsi.

 

Thanks for the clarification.

 

excellent information from everyone.