If its helpful having the jhm tune means your throttle input is active throughout the entire range. When your driving select the instant mpg calculation and when driving at a steady pace on the expressway try using ever so much less throttle input. You’ll notice your mpg is able to go up as you’ll see you can keep pace with less throttle.
Thanks - already have the JHM RS4 tune. I didn’t really notice any changes in mileage trends after installation, although I may have driven more like a hooligan, which kills the comparison. 
People often say it is better on gas after the tune because the stock tune is super rich to protect the car (stock tune assumes you will get shitty 89 octane gas and push the fuck out of the car, despite all the warnings)
If you lean out the Afr (maybe a bad choice of words…just not running it pig rich) to something more optimal for power, you should in theory use less fuel but I can’t say I ever noticed that on the old car.
At low load the target Afr is typically 14.7 to minimize emissions. Both stock and with most tunes.
Some of the numerous other ‘tricks’ in the JHM tunes could definitely help matters though.
Yep.
It averages 14.7 but it bounces around from a little rich to a little lean. I will on occasion glance at the AFR while driving.
004416 - Oxygen (Lambda) Sensor; B2 S2
P1140 - 008 - Internal Resistance too High - Intermittent - MIL ON
Happens about once a month now. Always on the highway after a relatively hard run.
Why not replace it? It’s about 100 bucks.
The 02 is on its way out. If it gives you that code after a hard pull it is telling you the 02 is dieing.
Gotcha.
Recommended to replace them in pairs?
Yes it’s always best to replace them in pairs. This helps keep the motor running in better ballance.
Ok - help me verify that I’ve got this straight…
Notation:
Bank one = passenger side
Bank two = drivers side
Sensor one = front oxygen sensor
Sensor two = rear oxygen sensor
Replacing a pair: This would be the pair sensors at the same location in the exhaust, i.e., the same sensor on each bank.
So… if my B2S2 is going out, then I need to order B2S2 + B1S2 to replace both rear O2 sensors on the car. Right?
Looking at pricing options for both sensors…
JHM = $455
ECS = $304
Jim Ellis = $297
Tip from another member: Rock Auto
I’ve never used them before, but they have some very low prices, relatively speaking!
Front = $144 for both (Bosch)
Rear = $233 for both (Denso)
Total = $377 for all 4 O2 sensors
http://www.rockauto.com/catalog/moreinfo.php?pk=1606896&cc=3003279
http://www.rockauto.com/catalog/moreinfo.php?pk=1606862&cc=3003279
http://www.rockauto.com/catalog/moreinfo.php?pk=3559644&cc=3003279
They don’t advertise, but get a quote from JHM. I only found out about their ability to get OEM parts for cheap when visiting them in California. They have been my cheapest option even considering shipping across the continent, conversion to CAD and import taxes.
Their process is (1) send them part numbers (2) get a quote (3) pay online via your own account (they make a custom “basket”).
I just had mine crap out, same thing really. I ordered from ecs and they were here in 2 days. are u stock exhaust data?
its a bit difficult to to reach the connectors on top of the tranny. I used a medium sized crow bar to pop the connectors out of their holder. because I have the jhm exhaust I have more room to get my hands up there to unclip the connectors if youre still stock u will have to fight a bit more.
then for reinstall I clipped the new ones in first, got them all back in place on top of the tranny and when I went to screw the sensors into the exhaust I twisted the wires in the opposite direction so they would be where they need to be when tight.
i think u may already know all this, with the new ones in i noticed an immediate improvement in smoothness and crispness during acceleration. you’ll be happy.
Thanks bango - will contact Jake.
Appreciate you sharing the experience, BT. I hope I’ve caught it soon enough that I don’t feel any improvements. 
S1 is the wideband pre cat sensor. It should be the double the price one. The ‘front one’
S2 is the after the cat sensor. Should be the cheap one.
Be careful that someone isn’t showing you S4 sensors.
Wow - been a while since I updated this thread…
Here’s what’s happened in the last 3 months…
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RS4 has crossed 60k, and running great. It especially loves the dense/humid winter air in Florida. Sometimes the temperature even gets below (wait for it…) 50°F!
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I replaced the two rear O2 sensors. No more MIL/CEL/DTC (pick one)!
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Over the holidays, I installed the ECS rear diff mount. A very simple install, that I can see no downside to.
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I have decided to upgrade the stock catback to the JHM catback at some point this year. Hoping they will offer another sale at some point. I already have the JHM DPs, so it will complete the set.
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Paint on one of my wheels chipped off near the center. Not sure why, but it left a quarter size chip that looks like it will spread as the edge of the paint lifts off the wheel. I’ll get them refinished this year.
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My BT streaming stopped working on my RNSE adapter. I sent it in to be replaced. The new one didn’t work. So I plugged in my iPod, and that didn’t work either. So this meant my stock Audi iPod connection wasn’t functioning… So I replaced it with a Dension aftermarket connection. That didn’t work… So this means my RNS-E isn’t seeing the iPod unit at all. Just slowly working my way upstream… No VAG-COM codes. I need to go double check the coding on the radio - but I can’t see why it would have changed from functioning to non-functioning. Will update as I continue diagnosis/trouble-shooting.
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I sold my 400 awhp built Subaru. Really nice guy flew in from NJ, paid cash, and drove it home. The guy that bought it had recently moved to NJ, and needed a winter car. He didn’t know much about Subarus, which seemed weird… I mean, who buys an expensive, highly modified car without base knowledge on the platform??? Turns out his friend is a rally car builder, and knew of me through many mutual acquaintances, and the quality of the car. He got one hell of a ride.
That’s quite an update. Well written too.
Weird about the ipod connection not working.
What does the decision do that’s better than the old one? (not a high bar…thr stock one is terrible lol)
For you downpipes are they tapered down for the catback or is there an adapter and they chopped off the last bit of your stock catback?
Yes great update.
The catback will be a great addition to the car. Like sakimano said check the dps if they have the neck down have a good muffler shop sort them out so there is no neck down.
These v8s love the cooler weather and below 50 man that’s rare but I bet fun. They also like to have all the maintenance done and it sounds like you have done that.
As for the Subaru that had to nice to see it go to a nice guy. And it’s good you moved in from the Subaru it sends mixed messages to car enthusiasts that see in your garage lol.
Thanks.
Yes, iPod losing functionality is weird. Didn’t get to troubleshoot today, like I had planned. Stay tuned.
I had tried the Dension before, and it does nothing better, other than slightly increased DIS functionality. The only reason I reinstalled it was that I thought the Audi unit gave up the ghost.
My JHM DPs have welded tapers (2.75 down to 2.5). According to Jake, it was designed so that you just cut the taper off, and they will hook right up to the JHM catback. WIN!