RE: urq cat "replacement"?

["Bruce Bell" <bbell04@ibm.net>]

> > My cat is in decent shape, and I would like to keep it that way.  So
> >  I want a spare cat to modify for track use.  I am hoping
> that a 5000t
> >  cat will fit, as they can be found in the junkyard fairly cheaply.
>
> Nope ... only the Ur-Q used 65mm exhaust tubing and the cat
> is unique to the
> car.  You don't even want to know how proud Audi is of them...  :^(
>
> JG

The stock 4kq cat, when compared side by side, has precisely the same ID and
flanges as the Urq cat. The 4kq cat does not have the flat plate at the
entrance and it does have provision for the O2 sensor.  The 4kq cat is also
a little longer than that of the Urq. The difference in length is made up by
the terminating location of the down pipe.  Which is why (tailpipes at the
rear valance excepted) the Ur-q cat back exhaust is a bolt in on the 4kq.
Watch out for aftermarket cats on the 4kq as some aren't the full diameter.
My test pipe (not currently in use) was made from an urq cat.

Bruce