I have recently had installed some bypass pipes on my 2011 CTT in order to reduce back pressure, increase power and reduce turbo lag. It did live up to these claims however there is a very annoying sound coming from my mufflers. The guys at SD Tint here in San Diego have been great in working with me to figure out the cause. We have spoken to the manufacturers (who I would like to leave anonymous) and they state this sound we are noticing is not expected. It does make a more throaty sound to the exhaust but under light acceleration and deceleration there is a loud repititive hollow sound which we are unable to figure out. The only thing we can figure is that the mufflers are either damaged or can not handle the increase pressure from the bypass pipes.

Want to know if anyone who has this mod has or has not had this issue.

 

Anyone have the bypass pipes on their Cayenne?

 

vid or sound clip would help...

 

I agree, but that is harder then it seems. It does not happen while revving it up in standstill. It only occurs while the car is under low to moderate acceleration and during deceleration. Also I am not very computer savy and would not now how to upload a sound bite or video to this thread.

For now just curious to see if anyone had any sounds that were not normal or better to say obviously unwanted and annoying. The manufacturer offered for me to send it back for a full refund. I would like to make sure I covered all my bases before giving up on it.

 

It's a raspy sound my 11 cs makes because of the bypass. It is annoying. I am biding my time until an aftermarket muffler that can take the flow comes out

 

This raspy sound is a well known "side-effect" of the secondary cat bypass pipes. Supersprint makes some high-flow cat pipes that might be worth looking at, however, any type of cat will diminish the power and mileage gain.

 

So you also think it is that the stock muffler cant handle the flow. Wish the manufacturer would say that instead of saying it shouldn't happen. Anyway, I was not planning on dropping over 3k on a new muffler for this car. The only other thing I was going to do was an EVOMS ecu tune.
I cant stand the sound!

 

I would not spend $3k plus on an exhaust system.... from what I can tell, the factory system is very well buit, and the only real bottleneck other than the cats is the HUGE factory muffler.... Why not have a reputable shop custom fab something to change out the rear muffler for you.... it would be much cheaper and you could customize it to your liking!

 

Thanks, that is informative. The high flow cats pipes dont sound like a good option for me.
When you say raspy sound, it does not sound very raspy or at least what I think is raspy. It sounds more of a loud hollow sound that is repititive. Not sure what I am going to do.

 

Took off the by-pass pipes and the sound was still there which meant it was the muffler this whole time. So the dealer is putting in a new muffler, and then I will put the by-pass pipes back on. Will let you guys know the results, hope it works out this time. Man was that a confusing process to figure out.

 

Is the gas mileage that much different with the bypass pipes?