ELJG

A search did not uncover anything on this, so here are some undoubtedly easy questions for the experts here. They were beyond the Porsche service manager's ability/knowledge . After the annual service I was informed that there was some sort of a noise possibly indicating that the cat on my 95 GTS was/is breaking down. When I asked how much to fix I was told they would have to check since they did not know if it was possible to change just the cat or much more needed to be done. Yes, it an official Porsche dealer!!! So is it just the cat, the whole muffler system or what? Thank you for the help.

Leon Speed

Hmm..if you here no noise and it doesn't bother you leave it alone..

In any case I would like them to tell me exactly what is breaking...never heard of a cat 'breaking', just deteriorating due to long use.

But if you are considering replacing the cats, now is a good time to buy an x-pipe with high flow cats.

bernard farquart

I have seen the "honey comb" type break down, you can actually get a section broken off the front part of the cat that turns sideways and restricts exhaust flow. I had one that rattled on decelleration so much, I was convinced I had a rod knock.

(shadetree warning)
If you are so inclined, you can un hook the exhaust in front of the cat, and put a good shop vac on it to suck out any pieces that have cracked off.

SeanR

x2

The cats are part of the down pipe from the headers, and extends back to the rear exhaust section. I would imagine that it is high $$.

Best route is what Aryan said, contact Rog100 here, a X-pipe with high flow cats will run way less $$ and gives you a bit more power.

Peter F

I had a slight rattling noice coming from the cat outer shielding which can come loose with time.(light tapping with a rubber mallet told the reason)
It took a friend with a MIG welder 10 minutes to fix on a lift in his garage.
(Remove battery and brain connectors first though before any welding)

/Peter

RyanPerrella

when a cat has expired, they usually end up clogging the exhaust where the car wont run, or they fall apart inside and rattle around like there are rocks inside the thing.

If you need a replacement, its a no brainer to go with the X-pipe with new aftermarket cats (10+ years has done allot for emissions components) These should be good for 20 HP on a GTS.

pmotts

I don't know where you live but you might want to investigate whether there is a known 928 mechanic in your area. Most of us would never take our 928's to a Porsche dealer. You might be lucky and and the dealer has kept a good 928 mechanic but most of the good ones are not at dealerships anymore.
Jim

Mrmerlin

What Pmotts said . You may want to get under the car and see if there is a stone other foreign debris in the exhaust system. Also take a careful look at the outside of the cats, (the belly pan has to come off to do this) and look for any crushing or scrapes in the cat outer housing, also noting the color of the pipes leading into the cats if they both dont look the same then you may have a cat that is starting to desintegrate, there are 2 cats in your system one for each bank of cylinders.
If nothing is obvious then you might be able to remove the cats from the exhaust system and flip them up to see if anything falls out of them. If you find parts of the cats falling out then you need a new set of head/cat pipes. You can replace the factory cats with the aftermarket X pipes and cat assemblies a lot less expensive that the porsche unit

SMTCapeCod

Right. COuld be the air tube, could be the heat shield, could be the honeycomb, sounds pretty vague.
I'd suggest....even given that it's a GTS, getting a Lomas or similar x pipe with the high flow cats and having an independent shop install it *just due to the convenience of having a torch and air tools on hand).
Failing that, I think Supersprint may offer high flow units too.

tomboyea123

If you need some gts cats, I have them.

Vilhuer

So many have changed stock cats to X that there are probably several hundred used cats available cheaply. No need to spend $2,722.97 for new cat.

Nine2Eight

So, what is the recommended "high flow" cat used with the x-pipe? Brand, price ??

Ketchmi

Magnaflow cats (400cpi ceramic brick) lost approx. 14 hp on the dyno in my testing. Random Technologies (300cpi spiral wound metal matrix) lost 7 to 8 hp. I had some made for our crossover that only lost 1 to 2 hp (100cpi spiral wound metal matrix) and pass emissions with flying colors if the car is capable of running in closed loop operation.

ROG100

I sell the best X pipe there is and it was designed by Dave Lomas (Ketchmi).
I have lots of very happy customers.
Aluminized X pipe is $399.95 and the cats are $299.95. Install kit is $24.99.
I have them in stock and ready to go.
Roger@928sRus.com

Peter F

Roger,

which one of the cat versions do you sell with the x-pipe?
/Peter