997 GT3 Cat replacement

[Fl0pp3r]

Hi all,

Looks like I need at least one new cat for the 7.2 exhaust (currently standard apart from rear muffler bypass)

Tempted to go 200 cell (OBVS) - but it’s pretty darned loud already and I don’t want any CEL issues, and reducing exhaust back pressure could hurt low rpm performance is that right?

Not looking to go nuts here so the FVD headers kit is probably not on the table.

Thoughts/experiences welcome

[SFO]

what mileage?

what do you think caused damage to the cat?

[Cunno]

I didn’t think there where any cheap options. OEM header + cat (one unit) were £1500 each side back in 2013 so your FVD options look good value. The only way of doing cheaper is to buy an after market cat and weld to header, but word of warning the cat on the 997 sits very close to the engine and if the material breaks up it can get sucked up back into the engine and destroy the piston liners and value train. I had this happen on my car running a after market exhaust with top of the range 100 cell cats. Unknown to me they had started to fail, span out at silly never stalled car kept it running but the cat material got sucked into engine big bill. So if you you are going aftermarket go quality and I’d also look at moving them further away from the engine. Standard cat is 400 cell I believe so anything less restrictive will increase noise.

[Fl0pp3r]

Cheers chaps, not sure it’s gone as such but it’s making a rattling noise and we’ll find out at MOT in a couple of months. Car’s on 30k miles.

If there’s ANY danger of engine damage with a high flow cat I might give it a miss and go standard tbh.

Both FVD & AWE cats are made by HJS Germany - not sure if this constitutes quality or not?

[Cunno]

Fl0pp3r said:

Both FVD & AWE cats are made by HJS Germany - not sure if this constitutes quality or not?

Yes it does or so I was told and paid for. In fareness I should add my engine isn’t exactly standard and this could of also had an effect on the cats. Saying that I found quite a few issues with aftermarket cats on rennlist which also had the same result as mine.

[isaldiri]

Fl0pp3r said:

Both FVD & AWE cats are made by HJS Germany - not sure if this constitutes quality or not?

If it's tuv approved it should mean it's made to a certain standard.

[Fl0pp3r]

Right oh, I’ll see what options I’ve got via OEM/Porsche first as I’m not looking for performance gains, but I’m not looking to get ripped off either and as you say a German TÜV product ought to be up to it.

[Fl0pp3r]

Great news - cat(s) are fine it turns out, rattle was coming from butchered clamps and worn seals. £300 vs £2,000+ (Manifold/cat replacement on one side) so a result for sure. Consensus remains you need to leave the headers/cats alone on these or you’re opening yourself up to OBD errors.