I was driving the ta and noticed some smoke coming from under the hood and pulled over to see what the problem was and could hear a clacking sound from underneath the car . I looked under the car and saw the cat was smoking babily from where its bolted to the exhaust. I think ive found my bad miss and low stumble problem ,though Im about to change opti,plugs and wires,plus add some jet hot lts ,would it better to run a high flow cat or offroad pipe with an a4,I know an m6 would be ok ,but since the 95 is an 4l60e would this loss of back pressure effect the trannys performance since it computer controlled any info would be greatily appretiated.
Thanks
Gary
95Ta

 

The cat is a major restriction on the exhaust. A high flow cat or off road pipe will remove that restriction and result in better flow and thusly more power.

 

perhaps, but the cat is a lot less of a restriction than the stock exhaust manifolds...

My understanding is that the modern cats in our cars aren't as much of a restriction as people believe...the honeycomb design in addition to the greater surface area since the cat is so big makes the cat cause little restriction. If your cat is smoking and red hot, it's probably plugged.

You won't lose any tranny performance or even motor performance going to a high flow cat, some people have noted a loss in torque going to an offroad pipe (when combined with other high flowing exhaust pieces, eg. headers, cat-back) but you won't pass emissions with an offroad pipe, and some people have had issues with passing with a highflow cat if they are running bigger cams.

 

Well emissions are not a problem here in West Palm Beach so passing the sniffer test is not an issue but a loss of torque could be maybe a high flow cat wouldnt be such a bad idea and I could always add a cut out for the track. Thanks for the info if any one else has any opinions Im all ears.
Thanks Again
Gary
95Ta