My Billy Boat downpipe kit is now installed along with four new O2 sensors. They had to fabricate a small reducer pipe from the cats to the existing exhaust system. It cost me $1000 for the parts and labor, in addition to the $1400 I spent on the downpipe kit. It took 12 hours to fit the system, but my indie guy is real decent and only charged me for 6 hours. CEL is currently off. I will take it on a 2500 mile run to Savannah GA tomorrow and will report back any issues including mpg changes. The A6 has just over 197k miles on her at the moment.

 

awesome.

interested to hear how it works out after the trip

 

Not a happy saga, but more to follow. About 180 miles into a 2000 mile long weekend trip, the CEL came on. Had it checked yesterday and not only was the P0401 back, but also both rear O2 sensors and both engine temperature sensors. We cleared all the errors and I will be driving it to WI next week. if the CELs come back, it may require new temp sensors or EGR (combi) valves.

 

Crapola. Drove it less than 60 miles on Saturday and the CEL went off again. Had it read Monday morning and it says both bank 1 and 2 cats are bad. Since I just replaced them with Billy Boat cats, I am a lot perplexed (and poorer). Cleared the CEL again and headed to WI for the week -- at 150 miles the CEL lit again. I am willing to pay more to have it fixed right, but I just don't want to keep throwing sensors into it and still have a CEL. I love the car, but she frustrates me. Dang OOOO.

 

That's what you get for getting rid of your precats! Anyways, nothing that a o2 anti fouler would not solve... About $10 and an hour of your time with your favorite drill would not solve...