B9 tuning options


Registered User
I’m going to get the s4 tuned in the near future and I’ve been looking for reliable tuning options, but I suppose I’ve always thought that APR might be the best option however I’m a little confused by their info - there seems to be the suggestion on their website that the basic stage 1 gains maybe as high as 430bhp but they say that they measured the stock car as having 397bhp ?!?! Surely that can’t be correct?
Does anyone have before and after APR dyno figures??
Any clarification or advice welcomed!
Btw the other tuner I’m considering is Litchfields


New Member
Hi Ben, I'm interested in finding this out too for my B9 facelift S4. Is yours the V6 TFSI or V6 TDI version?


Registered User
Mine is a V6 TFSI

I’ve used Litchfield to import and tune cars before, they’re good but APR obviously has a reputation for being a leading Audi tuner so I’d be interested in getting to the bottom of their figures.


Registered User
So I just spoke to APR who are fairly insistent that a stock S4 on reasonable 95ron is pushing near 400bhp ????
Can anyone confirm or refute that ?


Registered User
It would not benefit APR to claim that the power they measured on their stock test car was higher than it really was. However their UK website does suggest that they measured with 98 RON.

There's a thread on Audizine by APR showing what they did to develop their tune. They took the engine out and added lots of sensors so that they could monitor it better during development rather than relying on the car's own sensors which are for operational purposes only. I have to assume that this means that they can develop a tune with safety and reliability considered. moreso than tuners who have not used this method.

I haven't had an APR tune but I have used APR parts when I modified my B5 S4. I do rate their engineering capabilities.

Litchfield has a good reputation but aren't they GT-R specialists? I wonder if they would be inclined to push an S4 a bit further than it is wise to?

I shall note that for a turbocharged engine, the B9 3.0 TFSI does have a relatively high compression ratio because it has the Miller cycle designed in. That does add an extra complexity to tuning it.


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My mistake - they quote Audi own figures as 350 on 95ron and their stock figure as 397 on 98ron

Btw litchfield are not claiming huge figures for the S4 in fact they are suggesting that their tune offers 400bhp from base map with street or dyno tweaking. Obviously this is a bit strange if APR are suggesting that a stock S4 run on 98 Ron (which mine always is ) produces almost 400 as standard


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There's no way they make 400bhp on super unleaded standard! Standard form my s4 is no quicker than my old 290 cupra, different story now I've got a dtuk box fitted

I have had the APR Stage 1 tune on my B9S4 (V6T) for a couple of months.
Verdict - it is sensational as it synchronises the gearbox changes and power/aggression very nicely.
Its tractability, overall power, smooth torque and gearbox change synching are all beyond reproach.
I did not bother about Dyno as there is so much variability from their results and a very questionable level of competence with many of their operators, especially in respect of correctly applying ISA corrections and indeed how to correctly and effectively test a quattro 4WD system.
What I can tell you is from a number of two-way road runs runs at 16 celsius and 1500' AMSL and nil wind the 0-60Mph is consistently 3.6sec; 50-100Kph is way down to 2.6 secs. I use 98RON BP Ultimate fuel.
It is a significant increase in drivability and power from the DTUK which was good at the time.
So regardless of whatever BHP or kW figure (335-345 kW?) the results on the road are what really matters and my car is a sensational sleeper now and I cannot really see a need for any more power.
It has made an already great car awesome.

Happy days



Registered User
Thanks for the reply Dingah, that’s reassuring to know that APR are delivering the goods !

it’s a shame that someone, you or someone else hasn’t don’t the before and after dyno pulls tho!

im not after peak /max numbers, I’m a firm believer that it’s cheaper and easier to simply buy a faster car in the first place - however I am all about tailoring a your own car to your own needs and for me currently that means getting a tune ! It would just be great to understand the gains being offered by the various companies and I suppose part of that is getting a handle on where the stock performance ends and where the mapped gains begin !
Hey Ben:

I hear you mate but those dyno numbers contain great variance unless you base your results on calculating the relative increase in power and assume base power is 260kW. However, even that was in doubt as my 0-100Kph time was slightly better than Audi's advertised.
If I look at the rather generic torque/power graph for the APR Stage 1 running 98RON on their web site I would say in my case that is looking pretty accurate if not a bit pessimistic. - ie 330kW - it really flies.
From APR, this is what you get for the investment:
  • Fuel Grades - Multiple octanes from which to choose
  • Ethanol - Ethanol support from E60-E85 for maximum performance
  • Acceleration - Accelerate faster with more power and reduced throttle lag
  • Linear Throttle - Pedal maps adjusted for a more linear feel
  • Brake Boosting - Left foot braking or brake boosting added
  • Rev Limiter - Increased redline for higher revving
  • Standing Limiter - Increased standing limiter for higher revving at idle
  • Speed Limiter - Go as fast as you want with the speed limiter out of the way
  • Auto Start/Stop Inversion - Auto Start/Stop defaults to the off position
  • Exhaust Flaps - Enhanced power delivery and drivability through recalibrated exhaust flap actuation
  • Added Safety - Additional safety features and protection modes added
  • Economy - While cruising, or driving normally, your fuel economy may benefit from our optimized calibration
  • Boost Gauge - The factory boost gauge displays accurate boost and reacts more quickly
  • Power and Torque Gauges - The factory power and torque gauges are accurately rescaled
And yes I am a stalwart of APR .
I have tried other tuning enterprises with previous cars but have always settled with APR on 7 occasions now.



Registered User
Hey Dingah,

does APR offer car by car customisation or any street tuning options?
There are a few things in you list of enhancements that I don’t want - linear performance being the most significant! I’d like the engine to be a little more characterful , linear acceleration feel is an issue I have with many modern turbo powered cars ...Anyway that’s another whole thread ....
My point was , can you pick, choose or have bespoke optioned tunes with APR?
Maybe I shouldn't have posted that marketing cr*p from their website.
No it is not bespoke which is why I prefer it,
It is a thoroughly researched and exhaustively engineered solution that is the same for all purchasers.
That is why it is safe and that is why you don't spend countless hours fiddling around with an 'expert tuner' in the loop on a dyno slowly wrecking your drive train et al.
Yes I have had some 'average experiences' with bespoke tuning with some of the highly acclaimed experts and have no desire to ever go down that path again.
Please dig around and do your own research on APR and see for yourself - there are plenty of published data and articles.
As for not wanting linear power - seriously?



Registered User
Deadly serious!
A bit of turbo lag , a sudden surge of torque, an engine that comes on cam .... all things that make the driving experience more characterful and challenging in my book !

As for the lack of customisation and engine by engine tweaking, that’s a shame as far as I’m concerned anyway, I’ve had lots of success with tuners admittedly using ECUtek that have customised an tailored safe performance maps for many of my cars.

anyway I’m chatting to the APR guys and we’ll see what transpires...

in the mean time if anyone has any Dyno pulls of a stock S4 I’d be interested to see them regardless of how meaningful or not then are- if anyone has one, please post it on here



Registered User
Unicorn Motor Developments I'm Stockport! First and only tuner in the UK to be mapping the gearbox aswell I believe!

I'm currently running 0-60 in 3.3, 1/4 in 11.45@119.80 and 100-200kmh in 8.8

Theres waaaay more in it aswell, just waiting for dry roads!


New Member
I too would be interest to know what the actual outputs of a stock S4 is on 99 RON fuel from a RR session.
I run mine on Tesco 99, more out of habit, plus fuel is cheaper at the moment.
I had seen APR's quoted figures on 99 RON but understood the ECU was locked from advancing any further from a discussion I read here -> https://www.audi-sport.net/xf/threads/b9-s4-which-fuel.395407/

I know from having run two Fords with the 2.5 turbo 5 cylinder Volvo derived engine, that running on 97+ fuel would increase the output power by upto 5% (quoted by Ford in more obscure official literature). I remapped both Ford so they were were running at least 40 bhp more than stock.

I have the feeling that Audi may have locked the ECU so +95 RON fuel is no better deliberately on the B9 S4, due to the previous B8.X versions needing only a remap to keep up with an RS4 of the same generation.
If APR had unlocked the ECU, removed any code which prevented increased boost on 97+ RON fuel on that stock map, then run their tests, then it sounds reasonable the output was some 40bhp more perhaps?
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Here in Oz I use 98RON as it is the best quality fuel available here; it does carry a significant at-the-pump cost premium though.
For some absurd reason Australia has to endure some of the crapiest fuel qualities of almost any other country; 98RON provides the best chance of minimising the associated risks.
Any received improvement in performance is most likely due to one's wallet being considerably lighter in weight due to the high cost of 98RON.
Audi's can exhibit reasonable variance of power in stock form; more often than not they appear to exceed the stock numbers.
I advised my APR agency that my APR tune was to be based upon using 98RON as they appear to offer different options based upon fuel used.
Regarding Unicorn's tuning I suspect that maybe APR either subtly adjusts the ZF or maybe it's through dextrous use of timing, fuelling and boost shifts - either way the changes appear absolutely right for the conditions. APR do offer a separate software tune for gearboxes which I do not use. It's also interesting to note that Unicorn's reported outputs with Stage 1 are less than those of APR (420HP vs 441HP - 98RON) so I assume that the reported acceleration of nora's tune also includes other mods. If not then maybe my times are uber conservative - whatever..... it's now a great drive with linear power delivery!



Registered User
Apr dont touch anything to do with the TCU, thus the appaling looking graphs there tune produces!

Untill they do release a TCU tune they will always be playing catchup!


Registered User
Well then, please go ahead and explain?

It is indeed fact that Apr dont change any TCU parameters as per there thread on Audizine!

It is also fact no one with an Apr tune has come close to running an 11.3/11.4!

So please tell me, what was wrong?


New Member
Well then, please go ahead and explain?

It is indeed fact that Apr dont change any TCU parameters as per there thread on Audizine!

It is also fact no one with an Apr tune has come close to running an 11.3/11.4!

So please tell me, what was wrong?
Nora, are you running stock B9 S4 with Unicorn Stage 1 + TCU remap? Can you give a short review of how the car feels compared to before please mate?