Who has cat bypass on their cars? What are the power gains? I know Bursch has one, anyone made their own--how much $?

 

i made my own...40 bucks to weld a piece of 2.5in exhaust tubing in place of the cat. gains were felt slightly at about 5k rpm. there was just way too much popping for my liking so i got another cat.

 

About a month or so after I bought my 944, the cat crapped out on me, the internals basically fell apart. So I took it out, just like osu944, and put a straight pipe in there for now, seeing I dont have to smog it for another year and a half. Not sure about power gains, yet I do get a lot of fuel smells/ gas smells in the cabin. Not sure if thats because of the lack of a Cat.

 

Oh yea and total cost to do it was like 5-10 dollars.

 

Helps with the turbo's. Releases the back pressure and helps the turbo breathe better so you get quicker boost. You feel it.

 

Save your money. Removing the CAT lowers the exhaust back pressure and causes low end torque to drop.

BTDT.

 

thanks for the feedback

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Charlotte944:
<strong>Save your money. Removing the CAT lowers the exhaust back pressure and causes low end torque to drop.

BTDT.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">this being with the n/a's ?! right?

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by sybelix:
<strong> </font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Charlotte944:
<strong>Save your money. Removing the CAT lowers the exhaust back pressure and causes low end torque to drop.

BTDT.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">this being with the n/a's ?! right? </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">yea, on your 951 you will like the bypass since you will get on boost quicker (less restriction)

 

ok, thanks Dan
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

 

The Bursch unit is made with mild steel and will rust/crack after a couple of years if the car ever sees rain. It's worth it to spend the extra $ on a stainless pipe from any of the tunres.

 

Would there be any gain to be had by using 3" bypass pipe, if rest of the exhaust is stock or nearly stock (= louder rear muffler but still 2.5" (??) diameter piping)? I'd guess not, but it wouldn't be the first time I'm wrong...

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Sami951:
<strong>Would there be any gain to be had by using 3" bypass pipe, if rest of the exhaust is stock or nearly stock (= louder rear muffler but still 2.5" (??) diameter piping)? I'd guess not, but it wouldn't be the first time I'm wrong...</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">If I remember correctly it will not be as good as a pipe that is the same diameter as the cat back. You will actually be creating a baffle of sorts where the hot gasses coming out of the turbo will slow down and have a chance to cool a little. Don't get me wrong though, it will probably still give you a performance boost over the stock cat.
There was a discussion on the turbo page a while back about this very same thing and I believe that the conclusion was that the best exhaust would start out at the same size as the turbo outlet and gradually get larger from there (i.e. starting out at 2.5" and gradually expanding to 4" by the end).

Or maybe I have had too much caffine at work tonight and have no clue as to what I saying...
Where's Danno when you need him?

 

I liked how mine sounded with the Test pipe on, yes, it might have had a small loss of torque down low, but the upper end was very good! The growl sounds much better then stock!