Jmlinmn

I've recently taken my bone stock 2007 S6 and made the following changes to it. Here are my quick qualitative (i.e. not backed by any measurements) impressions based on the order I made the modification:

Airbox flap removal:
After reading pros and cons on this, I decided to remove the flaps on my airboxes. It's a pretty easy thing to do. I never work on cars and if you take your time, you can do this even if you've never done more than add windshield wiper fluid. The hardest part of this process is learning how to release the MAF clips without breaking them.

Impressions:
My airboxes were incredibly dirty - one had leaf/tree debris in it, the other had shredded bits of what looks like newspaper. I'm going to keep an eye on them now. I was surprised they were as dirty as they were.

The stock air filters were also in pretty bad shape. As far as performance is concerned, I think the sound from the engine bay is slightly louder, and I believe the car seems to rev more freely. I have no idea if this will ultimately raise intake air temperature and/or pull my timing. It's cold here (MN) when it's not July, so I'm going to take my chances for a while.

APR 93 Octane Tune
I really should have had pre/post dyno numbers for this...

Impressions:
The throttle response seems roughly about the same in standard drive. It does feel improved in Sport mode vs how it did with a stock tune. The car definitely pulls harder through the gears, most notably in 3rd and 4th. I have never wrung out the car in 5th and 6th, so I don't really have anything to compare that against. I wish I had dynoed this. DirtyVegasTT got great results with the 91 tune. I wonder how much beyond that I might be on the 93 tune? The car definitely felt "awake" after this tune. I did it during the recent sale, so I paid about $700, I think. It was worth it.

One con worth noting: this is a single program ECU upgrade, meaning you cannot switch between octanes and factory settings. My purchasing 93 Octane is a pretty significant commitment to 93 Octane gas. Any future roadtrips will probably need to be planned around quality gas stops and/or include octane booster sitting in the trunk on standby.

Milltek Non-Resonated Catback Exhaust
$1975 (including shipping) drop shipped from Milltek in the UK to my local performance shop (Imola Motor Sports - great place). Purchased through Stratmosphere.

Impressions:
You have to hear it in person - the videos on the net really don't do it justice at all. I'm still getting used to it. At idle and low-revs (putting around in standard drive) it sounds like a very deep V8 with a nice, somewhat threatening low rumble. You could drive your wife/kids, customers around in it.

When you really get on the throttle, it's completely different - definitely get more of that higher v10 sound to it as the revs climb. Winding it out and letting it shift at redline is a bit reminiscent of a Gallardo, even though the engines are distant cousins at best. At full throttle, people will notice you, cops will notice you, you will create a cacophony of sound in a tunnel and under a bridge overpass.

I don't believe I had noticeable performance gains from replacing the exhaust.

K&N Air Filters (part no: E-2996)
$115 for two: Nice drop-in replacement air filter from K&N.

Impressions:
If you've done the airflap mod, then you've already done more than what you need to do to get in there and change the air filters. It does feel like the car breathes easier / revs more freely. Please note that my factory filters were pretty filthy.

Outside of the above, I'm not sure that there's really anything else that can be done (at current) with the S6 from a performance perspective (other than an engine decarb). That's the last thing left for me to do. I would recommend all of the above changes.

Sox6

Great post. How much did they charge you for the Milltek install?

Jmlinmn

Thanks. $150 to install the exhaust. The APR tune + exhaust and it's a different car.

sgroer

Reading this makes me miss my S6, which I traded for a C7 over the weekend. I was headed down the path you detailed above, as you pointed out, it's a very clear path with little to no "forks in the road." I loved the exclusivity and allure of the v10, and the sound with the rear resonators removed was awesome. I've never heard a Milltek, but I am sure it's just superb.

I was always disappointed with the stock performance of the s6 - I felt like it had been incredibly detuned, and that if the aftermarket had paid attention to this car, it could have come to life in an amazing way. If you look at that engine in the r8 5.2, it's obvious the power is lurking.

The stock air intake is an embarrassment - it sounds like you got some help with the flap and filters mods. And that's where members have seen performance gains - getting more air to the engine. BostonS6 posted a couple years ago about his custom intake that put the filters right in front of the car, and he had remarkable results in terms of performance.

But I wasn't willing to go that far. I loved many things about it and miss the low end slam the v10 provides. It's a great car and it sounds like you've made it even better. Read up wherever you can on a custom cold air intake - I think that's where the ponies are hiding.

Sox6

I agree completely about getting more air to the engine. I have done the airbox mod and K&N filters as well, however I still think more air would make a difference. One of the biggest issues in the engine bay is limitation on space, there is just not room to do much different with the intakes. The other issue is heat. I am curious if anyone has opened up the sections along the lower front bumpers below the LED's? It looks like it should be open and pull in air, but both sections are sealed off. Not sure exactly what is behind both areas, and if water coming in would wreak havoc, but it seems like any additional fresh air would help.

Jmlinmn

I agree that more air and/or a custom cold air intake could make a world of difference. The engine bay is probably the most crowded engine bay I've ever seen. It's so damned hard to remove the top of the airbox on the driver's side and that's immediately accessible. I think to get really good, clean airflow to either side you'd need to commit a fair amount of money to modification.

I love the car with the modifications I've made to it, but it still feels like this engine could be an absolute beast if someone wanted to invest the time/resources into it. I'd be tempted to invest time/resources into it if I thought I could get a reasonable return off of it (i.e. something productized).
I'm guessing that a number of people before me have already looked at it and passed... after all, why not just buy a car that is more readily modified or that already has all the ponies you could want?

john_S6

I have all of the above except for the exhaust, I did remove the back resonator for more of a sporty sound. The only additional option I have is water/meth injection, which make big diferrence specialy above 3K RPM's. Other members have tried to squeeze the most ponnies from the v10 but engine space is always the big issue.

mplsC6S6

I just had the new STaSIS ECM update/tune installed, along with a Milltek Non-Resonated Exhaust at Carousel Audi in Minneapolis last Thursday August 11th.

I like the STaSIS update - car seems to pull harder and faster in the usual (pre-tune) spots: up to 3000rpm, and again at the higher 4500/5000rpm range - there is a noticable differance.

The Milltek non-resonated system is a bit too obnoxious for me (FYI I'm 34 years old if that helps/matters to anyone). *note I am a fan of exhaust notes and appreciate them for different reasons - I have a Fabspeed system on my Cayenne Turbo and love it! However, I am having the Milltek system removed next week and the original system put back in.

Anyone in or around Minneapolis, MN looking for a brand new (used 5 days) Milltek non-resonated system by chance..?

Sox6

I might be interested in the exhaust, sent you a PM.

mplsC6S6

replied to you PM - thanks!