The base-level tune is known as the APR Plus tune set up for 91-octane fuel. Though the least potent option available, it still adds in impressive 59 horsepower and 97 pound-feet of torque to the factory numbers for totals of 459 and 451 respectively. That's a big gain. And even better, the APR Plus tune includes a warranty on the entire stock engine and drivetrain for the remainder of the original factory powertrain warranty. The cost for all of this is $1,899.99.
The other option is the APR Stage 1 tune. This doesn't come with a warranty, but it has other advantages. First of all, it only costs $999.99. So if you're not feeling a warranty is necessary, you can get the same performance as the APR Plus for nearly half the price. The Stage 1 tune can also be ordered with calibrations for higher octane fuels, and thus can make more power.
If you're fortunate to live where you can get 93-octane fuel, the tune can bring either Audi up to 476 horsepower and 470 pound-feet of torque. For maximum power, there's an E85 version. This will let an RS3 or TT RS produce a stunning 542 horsepower and 500 pound-feet of torque. It is worth noting that this tune is meant for only E85, and it won't automatically switch to a less aggressive tune should you decide to fill up with conventional gasoline instead. APR does offer a program switcher for $149.99 that will allow you to cycle through different tunes manually.