The 2.0 Liter B48B20 and 3.0 Liter B58B30M0 turbo engine of the specified BMW models is equipped with an indirect charge-air cooling circuit. So the cooling of the charged air is not realized by the ambient air as cooling medium (as usual), but made with its own cooling water circuit. A reduction of the temperature of the cooling water is directly equated with an improved cooling performance of the charged air. This is exactly where the advantages of the WAGNERTUNING upgrade radiator comes into play. The new developed competition racing core of the WAGNERTUNING high performance radiator increase the radiator volume of the OEM water cooler by a total of 117 %. The calculated ratio between the inner and outer cooling surface generates a maximum heat transfer and allows at the same time enough air flow for the surrounding components (for example the engine radiator) for its own heat exchange. Furthermore, using an increased amount of cooling water, the entire system thermics can be kept at a lower level over a longer period of time.