Wsup everyone,
my name is Dan im a new user, and I have just purchased a 2005 Cayenne V6.
I wanted to do an exhaust settup on the car, and was thinking about running cats, then straightpipes, then the tips...I would like some feedback on the subject, I was wondering how you guys thought it might sound, and if you think there will be any downfall for the computer or motor. Thanx Dan

 

Hey Dan,

I have a 2005 Cayenne V6 i did the cat bypass pipe and the Turbo Tips with BMC Air Filter waht an improvement i got about 20 to 25 HP INCREASE WHAT AN AWSOME INPROVEMENT !!!



Marco

 

Is bypassing the cat road legal on such a new car?

 

To answer the specific question, Dan asked could he leave the cats on, and just run pipes back the the tips, with no mufflers. The answer is yes. It may be illedgal if the law requires muffler, but . . . . It will be loud, however. Not as loud as full straight pipes - the cats do act a bit as mufflers, but not much. Further, it probably will not have a nice sound (i.e., one you like): unmuffled, the sound of most engines is crackly and sharp, more like an nasty outboard motor on a boat, not the deep tone many people expect (the deep bass comes form the right type of resonator and muffler. You MIGHT want to consider switching out to a good aftermarket exhaust, or removing the mu8fflers and installing resonators (if you don't know the difference, a good shop will).

Now another comment:
Bypassing the cats is illegal. I'm not being a goody-two-shoes here but I am dead set against it. It is also sort of nasty illegal too because it violtates both state and federal laws and can get you in severe trouble if you get caught. But few people who remove them get caught, particularly in states like where I live, where there is no tight "visual inspection." Still, I don't do it and I consider it "cheating."

As to claims of lots of power from removing them or from "gutted cats" (removing the insides) -- I've never seen a stock vehicle pick up a verifiable (that means measured on a dyno) 20-25 HP improvement by removing the cats or show a noticeable improvement in 1/4 mile acceleration time with them removed. Most back-to-back dyno tests I've seen of cars with stock engines with cats versus the "off road" no-cat replacement pipe show less than a 3% difference, and I saw one car that lost HP (it needed the exhaust backpressure, not that uncommon). Further, I'm certain that if the Porsche Cayenne 6 was losing that much HP to the cats, Porsche would switch to larger cats to cut the HP loss: Realize that cats are available in many cross section sizess and each size is designed to interfer very little with power up to a certain flow - beyond that you upgrade.

On heavily modified cars, such as my vette and Camaro, you often lose a lot to the cats because you can't fit large enough cats into the space you have under the car. The vette picks up a verifiable 29 HP, the Camaro, about 40, when you remove the cats. But we still run them -- you run the largest ones you can -- but there is not room under the car car to run the size you really need. But we have electric cutouts that we can open at the track that dump the exhaust out ahead of the cats anyway. On the street, we always run them, and the mufflers.

 

Yes Lee, I thought as much. Here in the U.K. you can remove the cat on an older car (upto about 1991 I think) and still be legal, but remove them off a newer car and it would fail it's yearly Ministry Of Transport (M.O.T.) Test. So to get through this test, you would have to keep the cat and replace it for the test every year.

I've actualy removed the cat on my 944 (1990) as it was blowing (another M.O.T. failure) and compaired to a new cat the bypass pipe was a whole lot cheaper!

 

was it easy to install?

 

Straight pipes on a Cayenne or Touraeg would be very loud. You need to keep one set of cats in the system, or you will freak out the O2 system and throw check engine lights. If you want a very aggressive sound, do secondary cat bypass pipes with a Fabspeed muffler. Not only will you lose a good bit of weight, but the car will sound like it should have from the factory.

 

How easy is to install a Cat Bypass on a V6Cayenne.
Thank you.

 

It isn't too difficult if you have the correct tools to get the top nut off the 2ndary cat pipe. You either need about 4 feet of extensions, or a half moon wrench.

 

what are some good exhaust tip companies for an 04 cayenne S?