A big thanks to the Sline88 over at the OzAudi Forums for organising this Dyno Day.  I must also thank the guys over at 999 Automotive, Coopers Plains for allowing us to use their dyno.

This gave me a great chance to get the RS6 on the dyno again to see if the APR exhaust and high flow cats made a difference.
 

Short answer. No. 

Ambient air temp according to the sheet was around 23 degrees.  Final run produced 250.5kW with 531.5NM of torque.  Chatting to the guys there was around 2 to 3kW difference between the 3 runs.

Larger copy here if you want it. 

Interestingly though, this chart shows Tractive Effort (N).  From what I could work out from various sites you can convert this back into NM by taking the tractive effort then multiplying that by the rotational diameter of the tyres then dividing it by the gear and differential ratios.  I ended up with 7600*.330/4.718 which works roughly out to the 531NM mark.

The stock car ran 257kW and 535nm.  The modified exhaust produced the same power. Looks like the stock exhaust is going back on. As someone has pointed out though, this could be because the exhaust was designed around the APR chip.  The better flowing exhaust may be beneficial to the higher boost and power that the chip produces.

I was getting the flex joints fixed on the exhaust system so I decided to get new catalytic converters and a cat back exhaust system fitted while I was at it.

The catalytic converters are now 200cpi high flows and I got my hands on an APR RS6 Cat Back Exhaust System.  The APR kit is a stainless steel, mandrel bent, cat-back exhaust which runs dual 2.5" pipes.  More information can be found on the APR website http://goapr.com.au/products/apr_exhaust_rs6.html

The work was done at Mild 2 Wild Exhaust on Moss Street at Slacks Creek (07 3209 3309).  The guys down there knew what they were doing and did an excellent job.

Comparison time. First, a couple of shots and videos of the stock cats and exhaust.

Now for the high flow cats and APR exhaust.

I managed to quickly shove my head under the car after they finished.

They put flanges before the cats which sit fairly close to the transmission sump.  I've got the car booked in for a scheduled service in 2 weeks so I will have a look to see if its rubbing or hitting when its on the hoist.  The slip joints after the cats were kept in their original location so if I ever want to go back to the OEM exhaust there shouldn't be a problem.

Im not 100% sold on the new system yet.  While it doesn't sound overly louder outside the drone inside is quite a different thing.  Between 60 and 70kph with slight load the drone is very noticeable.  Cruising at 100kph on the highway is ok with it being only slightly louder than the stock system.  It's just a pity that it drones every time your around the 1000 to 2000rpm mark with load.

It's early stages at the moment but I personally think that the stock exhaust sounds better, at least while it's free revving.  The drone is the major downside for me and the power gains, if any, have yet to be seen.  Are the quad tips really worth the in cabin noise?

Total cost from Mild 2 Wild was $880.  This included the new cats, flanges, custom pipework and fitting the APR exhaust.

For now, the stock exhaust sits in a shipping container.

Drove down to Coolangatta Airport this morning.  After picking a couple of friends up the Airbag light on the dash stayed lit. 

Plugged in the VAG and got 00588 - Airbag Igniter - Driver Side - N95. 

Reset the fault and it hasn't come back yet.

Checked out a couple of websites after I got out of the car and found this little piece of advice "When "Short to positive" or "Short to ground" is found, DO NOT CLEAR THE DTC. This can cause the airbag to deploy. See repair manual for more information." 

Thankfully I didn't set the airbag off.

Pulled into the car park this morning and heard an unfamiliar sound coming from under the car.  It seems I've managed to damage the drivers side exhaust flex joint.

Well it happened.  Front windscreen managed to get a stone chip on the way to work.  This will make 2 front widescreens when I get this replaced.

I was digging through the old parts that I have sitting around and I stumbled across my old rotors and pads.  Since I was buying new rotors and pads I let the previous set wear very low.

This is one of the front pads.  The wear indicator studs are clearly visible and it looks like part of one of the indicators has managed to rip the pad through the centre.

This is reflected pretty badly on the rotor as well.

It appears the studs are a lot harder than the rotors.  A good reminder to replace the pads before they wear too much as it will be cheaper to replace them rather than a whole rotor.

Upon inspecting the RS after the last unscheduled visit to Audi I found that they have misplaced my tow eye.  Couple of weeks later my new one arrived.

Part number is 4B0805616A.

I can now venture outside of the metropolitan area without the fear of my new suspension being using to pull the RS6 onto a tow truck.