1999 Audi A6
Turbocharger

The Buy Auto Parts brand is an aftermarket version of the stock KO3 turbo. The Buy Auto Parts “High Performance” brand is an aftermarket upgraded KO4 turbo. The aftermarket stock turbo is a direct bolt on, but the upgraded aftermarket turbo will require additional upgraded air inlet piping. Our part number for that kit is 40-90011 PO.  The upgraded turbo with just the upgraded piping will increase the horsepower by about 50-60HP. With additional upgrades like tuning the ECU, upgrading the exhaust system, and so on you can get upwards of 100hp increase.

This is a brand new, high quality, aftermarket turbocharger is a guaranteed exact fit replacement for  the turbocharger that originally came in your vehicle.

Unfortunately we don't have that information. You might want to purchase a repair manual from a local parts store to find out or install a boost gauge.

Thank you for your inquiry. The kit includes our brand new turbo. The OEM turbo is made by the original equipment manufacturer, which is the one that Audi uses. The OEM high performance is the upgraded version of the OEM unit (K04 upgrade), which would give you more horsepower.  The other high performance option we have is our brand K04 upgrade.

Thank you for your inquiry.  The stock OEM turbo is set to put out a total of 150hp as where the high performance can put out up to 240hp. The OEM high performance is the same as the high performance with the exception that it is made by the original equipment manufacturer.

This K04 turbo (40-30015 HP) is our own brand, which we manufacture. It's guaranteed to fit and perform identical to OEM, backed by the same one year, unlimited mileage warranty. We also have an OEM BorgWarner AirWerks K04 available here:

https://www.buyautoparts.com/buynow/2002/audi/s4/turbocharger/40-30015_AW