New CAT. New aftermarket or used Porsche OEM?
 

After the issues I've been having with my engine (spluttering when hot after a hard drive, fine when driving normally), I'm pretty sure it's the cat. The sound is coming from the rear N/S, and it sounds like a blown exhaust after a while of driving hard but goes away after a while of driving carefully.

Here's a couple of videos I took of the problem:
https://www.youtube.com/watch?v=i69lltfykW8
https://www.youtube.com/watch?v=tyKCsiF_RJo

I assume I'm correct? I've seen a few things online of cat's failing, and having symptoms of rattling and spluttering when hot. It's exactly what I'm getting and sounds it too. A forum user on here is kind enough to let me borrow one of his cat's he has lying around so that I can see if it is the issue.

If it is, do I buy after market new, or OEM second hand?

The after market new one is here:
React Porsche | Euro Car Parts UK

Or I can get a used OEM Porsche one from Ebay for around the same price.

Buying a brand new OEM Porsche cat is absolutely out of the question as I can't afford it.

Thanks!

If you had a bad cat, the car would be throwing codes like crazy.

It sounds like you have an exhaust leak.

I would have a Porsche mechanic verify with codes that it is in fact one of the cats, you have 2 how do you know which one it is? They also have heat shields that come loose that cause noise sometimes too. You could just have some type of a bad exhaust leak somewhere. If one of the cats is bad you will get a check engine light on the dash. Find out exactly what's wrong before you just start replacing parts.

But it only happens when hot and after driving hard, heating up the car. Driving carefully makes the exhaust return to normal.

Are you throwing a code?

None at all. Also checked and no pending or stored codes.

Then it is not the cats.

I suppose that's kind of good news? Just hope the blow is somewhere that can be repairable.

Compared to jumping for new cats, it would be excellent news. It could be a blown gasket or seal, or a cracked component. If is a crack, it may be weldable, or in the worst case replaceable. In any case, you really do not want to have to spring for new cats, they ain't cheap by any stretch of the imagination.

I have a friend who was willing to lend me his. But I completely agree.