Anybody bought 3.0Q cats recently?

About 3 years ago I put on a Milltek cat-back system (from an S4 because it's the same fit) and at the same time I had a garage gut the precats and chop off the main cats, replacing them with a couple of unused S8 cats given to me at some point. All was well until recently, when I heard a rattling inside one of the cats, which i'm fairly sure was a bit of broken off brick/mesh/honeycomb.. a bit of the internal gubbins. I don't know if it broke off the main cat or if the precat wasn't gutted as I originally thought. The rattle stopped but I've noticed that the exhaust gases aren't come out of that side at the same rate of flow as the "good" side. Also the right rocker cover gasket has developed a small oil leak, which I'm assuming might be related to a build up of pressure in that side.

So anyway I'm not going to pay dealer prices for new cats because they are crazy. like 2 grand crazy. So i'm looking for alternatives. The car is Nov 2001 (one of the first B6s I think) so it needs a type approved cat. Ebay is looking like about £220 each or about the same here http://www.cats2u.co.uk/28524/Catalytic-Converter/AUDI/A4/3.0

Before I buy does anyone have any input? I'd really like to change both cats and then change both rocket cover gaskets.
cheers¨nj

Sam, great to hear from you. I'll try to find out if the S4 cats will fit. I know Milltek doesn't list their cats as being suitable for the 3.0Q. hmmm....

I can't find any info to say that the S4 cats will be the same as 3.0Q. I'm sure with a bit of work they could be made to fit but there's also the potential for that to turn out to be a lot of work. I guess it all depends on the various bend and length of the pipes.

Sam - cheers. I'll look into that. As per our emails, if the likes of JHM and Miltek don't list their S4 cats as being suitable for the 3.0Q there must be a difference at the manifolds or something. I'm not sure how much longer I'll be keeping the car so I don't want to go nuts and spend a fortune.. especially having just forked out about 750€ for a set of new winter tyres and alignment. Check these out http://www.nokiantyres.com/winter-tyres/nokian-hakkapeliitta-8/ and that's only 16" for my winter wheels.

Alex - Cheers. that's actually what I did last time. Kind of. At the same time as fitting my Milltek cat-back I had the pre-cats gutted and the main cats chopped out. I replaced those with 2 new S8 cats that someone had given me. All was well until recently and I know the whole cats will need to come off to see what's happened. So at that point I'd rather have new cats put in or a proper custom job done. Preferably without sending a fortune

yeah there's not much point in having full-on winter tyres in the UK. And you couldn't use them if there's no snow on the ground I believe? But over here I'll have them on for the next 5 months. The difference with studded tyres is just amazing. I remember trying to drive in Glasgow on summer tyres in the snow and even with quattro it was a slow and risky experience. When we have decent snow here I'll try to remember to make a short video to show you the take off... assuming my engine hasn't exploded by that point

yes, that's right mate. cat back is the same. I installed the Milltek, which has a join like an X pipe in the centre. I'm not sure whether I can say that it makes a huge amount of difference but there's comfort from knowing that the pressure is evenly distributed throughout the system. In my case the resonated pipes I bought had a big chunk of old catalyst material inside (much to the surprise of me and the the seller) so the back pressure could have caused problems if it was 2 separate systems for each side. Do you have a system in mind? The milltek is quite noisy, which isn't a bad thing unless you really want it quieter. But a full stainless exhaust is probably going to be like that from any manufacturer I would think.
cheers
nj