Just sharing my experiences as I found limited feedback and genuine owner experiences when I was seeking remap options and guidance (though thanks to those limited few who could advise).
I've owned my S4 for almost a year now. It's a 2009 DSG variant and whilst the original stock platform was good, it wasn't as thrilling as I believed it could be. With the sports diff, adjustable suspension etc. I was sure it was capable of so much more, even for spirited road use.
So after a couple of months ownership I went with a stage 2 APR upgrade, that consisted of remap to ECU (removal from car and hardware interface to apply), then installation of a new pulley to the supercharger. This took the stock car from being good to being great. Service from APR / Awesome GTI was fab.
In terms of the drive ... torque was noticeably increased and the engine would now pull hard to forced upshifts at around 7K, removing the plateau of power delivery that was enforced at just over 5K in stock form. The car now made me smile when pushing on and made it far more engaging, able to extract and use more of what the engine offered.
Stock my car reported around 340ps and 330nm. The APR stage 2 upgrades took it to approx. 425ps and 516nm
Time passed and I grew accustomed to the added oomph... in that time MRC had just also released their own stage 2 upgrade option - consisting of remap and pulley (although they replace the Engine drive pulley rather than the supercharger drive shaft one). So impulse took over one Friday afternoon and after a call to Doug at MRC I was booked in for their attentions the very next morning.
The work took around 3 to 4 hours as expected and the only added hardware was a replacement induction pipe from std. air box to s/c inlet (I'd already replaced the stock filter with a foam upgrade). I should make clear also that I only ever run the car on 95 RON fuel, I know that's not optimal however I only have to pay 40% of the fill up this way due to a fuel card.
That was around 3-4 weeks ago and I have to say, that it's taken what was a great delivery and made it simply fabulous. Torque is increased everywhere, and it's all so progressive and usable with predictable delivery. Top end grunt is simply fantastic compared to stock.
Despite my needing to run it on 95 Ron fuel it still reached 464ps and 575 nm with Dougs stage 2 map. He suspects another 10 to 15 ps could be found on some 99 Ron fuel. While the figures show a further 10% increase in power and torque, it is the delivery that has surprised me the most – it feels smooth as silk. Doug did mention something about secondary throttle valve or something which he uses to flatten some of the delivery, though I wasn't really listening at that point as I wanted to get on the road to try it out.
I just love how versatile this car is, from wife pootling around, to taking our large dog in the back and then occasionally surprising the odd sports car - it really is the best daily driver I think I could imagine presently.
It's all just so linear and useable... Goes from bugger all, to bugger me, to bugger this so deceptively easily.
So for anyone considering a remap to their S, I'd have to heartily recommend looking no further than MRC.