Ball bearing 4.0TFSI turbo upgrade, compatible with all 4.0t Audi engines, s6 s7 rs6 rs7 s8. Requires a core exchange (send in your old turbos). We use a GT28 or GT30 ball bearing cartridge to increase output by over 25% without sacrificing spool. Core can be any model 4.0T turbocharger. We have sets ready in stock to ship out so that your car wont be down more than a day. Includes OEM 5axis cnc'd oil and water adapters to preserve stock lines. GTX28 GTX30. These are available with genuine Garrett cores or equivalent proven ball bearing cartridges for a discounted price, both carrying the same one year limited warranty.