Started out with a drone and some vibrations and then a prolong loud exhaust sound. Thought it was something that has come loose or a small crack in the muffler.

It turned out to be a large piece of muffler that has broke and blown off, check out the hairline crack around the opening.

 

WOW! how did this happen?

is this a factory PSE or a, install after the purchase? i haven't seen something similar before!

 

It could be repaired, just cut off the damaged area and weld back a patch (stainless stain) of the same thickness.
How is the condition on the other muffler?
What is the car mileage and do you set the PSE "on" all the time?

 

We all want to know the particulars please.

 

That's the factory "Super Double PSE" from the factory. Jk


Jokes aside, I wonder about the details myself, especially what Porsche would say assuming early age, no salt, no mods, etc.

 

The car is a 2006 Carrera S X51 (factory installed PSE) with 34000 miles.

Yes, I have a bypass switch so it is in loud mode all the time.

The shop repaired it by putting a big stainless patch around it about 3 times the width covering up all other fractures.

I think my high flow cats may be a contributing factor for this???

 

Possibly you hit something? Caused the hairline fracture and then it got bigger over time and just blew with the pressure.

My .02.

 

The hole is on part of the muffler that is not visible even when the car is lifted up thus I don't think I it was outside force that caused it (we didn't see that big hole until we removed muffler from the car.)

 

It seems to me that a fracture of that magnitude would require a tremendous amount of pressure to blow out that way... unless maybe the PSE being open all the time was causing very hot gasses to be focused on that spot.

 

Any water or other liquids that can run down or drip down on that location?

I'm thinking hot from running the car - quick cool down from dripping condensation, water, etc... and repeat hot-cold-hot-cold.... the rapid cooling locks in stresses quickly and the structure of the steel could then become very brittle making it susceptible to fracture form vibration.

 

There could be issues that might cause the type of fractures seen in the OP's muffler. It's possible a sigma/delta phase could have formed. But the exhaust would have to hit 1200F and have a fairly high carbon content. Not likely in an an OE muffler.

It would have been interesting to have had a piece to look at.

To the OP. Do you have any idea of what grade of stainless they used to make the patch and which filler wire they used? Hopefully they drilled a hole at the end of each crack and used a filler metal to close it. Otherwise the crack might continue to propagate.

 

I have no idea what grade ss they use to patch it, it's the same material that the shop use to build custom mufflers. I am pretty sure they didn't drill first to stop the crack,, will have to wait and see.

The muffler shop did told me he has seen a few Porsches that does similar things (997 GT3) center mufflers, his theory is too much pressure going into the mufflers because the hi flow cats weren't as restrictive as stock.