@Class_5. That is very helpful. Will investigate further. Many thanks.

Update: Direnza don't seem to do Cats for the 2006 4.4L Petrol. Which ones did you go for Class_5?

Hi Gyre8 - I went for the Direnzas.

I've had a quick 'Google' and you're correct in that it seems to be hard to find aftermarket Cats for your 2006 model - I'd hazard a guess that's why someone has tried to make some aftermarket cats for another model to fit by welding...

I suppose your options are 2nd hand (eBay) or one of the custom exhaust fabricators.

Might be worth looking at eBay for new aftermarkets. As I said, I can't fault the Direnzas, stainless seems to be of good quality and being a bit better flowing the V8 sound is just a bit more prominent at idle when listening from outside the car.

Good luck.

Eddie

Looks like I'm going down this exact route, as I can't find suitable after-market Cats.

Few more question please Class_5:

Which lambda sensor spacers did you fit?

and where did you source them from?

A direct link would be great if you have it.

Also, I wonder if I'll need lambda spacers with a non-lpg, petrol engine?

Many thanks.

Lambda spacers were from eBay, just enter lambda spacer in the eBay search (they are such a simple thing that I don't believe one 'brand' is better than another). You must make sure the internal and external threads are correct. I went for the right angled versions as space was tight.

Now here's the thing - if you fit aftermarket Cats, you may or may not need the spacers. The theory is that a lot of aftermarket 'sports' Cats are 200 Cell/CPSI which makes them less restrictive than 'standard' Cats. So, although they pass the MoT emissions test without a problem, sometimes the post Cat lambdas will 'see' the slightly increased exhaust flow as a failing Cat and throw a CEL error (engine management light comes on).

If you look at Sabaru forums where folks seem to like fitting big bore exhausts with sports cats you'll see lots of posts about lambda spacers. Seems you can have exact same car, exact same aftermarket Cats, but one car will will be quite happy without the spacers, the other will illuminate the engine management light (as mine did).

So, if you go the aftermarket Cat route, fit new lambdas without the spacers and see what happens. On the L322 M62 V8 the post cat lambdas only monitor the 'quality' of the cats, they don't have any influence over fuelling. Plus (with the L322) it can take quite a while/distance driven for the post cat lambdas to throw an error which triggers the engine management light - I could drive mine for 75 miles after clearing the fault for the light to come back on.

My engine management light was coming on with the new cats running on petrol.

Oh, and please don't think you're alone with RR woes, there have been a few occasions when I regretted getting mine...

Cheers,

Eddie

This is very, very helpful information. Thank you Eddie.

I will try without spacers first, as you suggest.

A bit concerned about how much louder the FFRR will be with Sports Cats on. I don't want it to sound rough or noisy.