ilsaccente

I've got an A6 2.8q with 169,000 miles. The flex joint on the driver's side cat just blew, and the passenger side looks pretty bloated right now.

Had CEL code - driver's side cat below threshold - before flex joint blew; now there's no CEL at all. This leads me to believe that the passenger side cat is still good.

My questions are as follows:
1- Should I replace both cats, or just driver's side cat and passenger side flex joint?
2- At 169,000 miles, should I use OE or unversal cats?

Thanks in advance.

4Driver4

Bet that you can replace just the joints and the CEL will disappear. A blown flex joint will throw an efficiency CEL. On the 1999 cars, there is a single cat on each side. To throw a CEL for efficiency there needs to be a catastrophic failure; if it ain't rattlin', it's probably good.

That said, you can get aftermarket cats with new pipes from CT Cat for about $350 a side.

Donuts

Exhaust Direct (www.exhaustdirect.ca) for $190/side + $19 S&H. Ask for Jim Yanch. I bought both a left and right for my '99 and had no issues what so ever. They will warranty them for the federally mandated period too.

4Driver4

These are bolt in? Good fit?

ilsaccente

Oh, yes, I'm familiar with the cats at CT cats - great prices - that's where I was prob going to order from.

I WAS getting a code for just the driver's side cat, but that seems to have resolved. There is NO CEL codes at all now that the flex joint on the driver's side is blown.

Logic leads me to believe that if repairing the leaky flex joint (prior to its blowing) would cure the CEL, then the flex joint being completely blown off now certainly shouldn't elimnate the CEL.

I'm concerned about passing emmissions. Would you rec'd that I only replace the driver's side cat and the passenger side flex joint, instead of both cats?

Donuts

Completely. The driver's side on my started to break down with 115K on the car and threw a code. I had bought from EXD before for flex joints and some other stuff so I called Jim to see what he had. Told me he had both for AHA and ATQ models...provided me all the specs on the them and outlined their warranty policy so I pulled the trigger. Been 12 months so far with no issues and I even had my CT emission renewal done in Feb.

ilsaccente

I have to say, $190 per side is very tempting. You did the install? I was told that event he cats from CT cats don't always fit exactly like the OE one's. I heard sometimes they may need to be manhandled, heat shields need to be moved around.

4Driver4

I've never had a problem with CT Cat stuff. Never used anything else.

If you do elect to change the cats, replace the sleeves where they attach to the rest of the exhaust. That's a common leak point.

ilsaccente

I was going to order all new hardware from my buddy that gets me original and aftermarket Audi parts through WorldPac for cost + 10%.
Have you replaced the downpipes an cats on your '99 A6 yet? If so, did you have any problem with those old manifold studs? I'm a bit worried- any tips for me with those?

Donuts

I didn't want to deal with the install since I didn't have access to a lift. I provided the complete units, two new clamps and two gaskets to my mechanic.

He pulled the old and put on the two new with no issues in two hours. I don't make a point of plugging vendors but when I've had a good experience I will certainly share.

I did weight this choice pretty heavily given what I heard about aftermarket failures vs. OEM. I talked to Jim about failure rates and he was honest that initially they had some a few several years ago but had put a bigger cat which solved the issue. He also then highlighted their warranty and put it i writing for me. I also considered CT Cat since they are local but the price, discussion with Jim and past experience with EXD tilted the scale to them.

Just my $.02. :-)