raj99

OP, everyone here has given you sage advice. There is a guy on the forum that's made it his mission to extract more power from the S6, however he's spent more than the purchase price of the car in an attempt to do so. Therefore, the simple answer is that there really is no after market 'go-fast' mods/parts for your car. However, if you are willing to spend a heck of a lot of $$ - engine removal, custom piping, new manifold, etc...yes you can extract more power from it. But then again the latter applies to almost every vehicle - yes given enough money and time, you can do that with everything.

SchwarzS6

I think what this discussion points out is that car makers have done a pretty good job of maximizing the power out of a specific displacement for normally aspirated engines. They have to do this in order to meet CAFE standards. Putting in an engine which has more displacement (weight) than necessary and then not tuning it for maximum efficiency and power is costly to the company and the consumers. This is particularly true for naturally aspirated engines such as the V10 in the S6. In the old days you could remove the engine, bore out the cylinders a little for more displacement, shave the head for higher compression, replace the cams and valve springs to allow the engine to rev higher all producing more power. With today's computer controlled camshafts, rev limiters, O2 sensors, etc. doing this requires more than just a knowledge of mechanics, it would also require a custom tune and be very-very expensive.

Even the turbocharged engines are pretty well optimized but because there are tradeoffs there is room to make "improvements". Remapping the intake pressure by controlling the wastegate or the turbo vanes makes it possible to tune the power curve. In the case of a turbocharger you also have the option of putting on a larger turbo and a larger intercooler to get more HP at the expense of turbo lag. You can make similar upgrades to supercharged engines (change the gearing of the supercharger drive) but there is usually a trade-off in terms of drivability or fuel economy. The advantage of forced induction is that you can modify the power/torque curves with just a new map in the ECU which is pretty economical. Some of these tunes are even sanctioned by Audi and can be done without affecting the warranty.

These days if you want to tune for more power, start with a turbocharged or supercharged engine and you will have more options.