DBA 4000XS Cross Drilled & Slotted Rear Rotor Impreza WRX STI (01 07) (DBA4656XS 10). Notes Regarding Vehicle Compatibility: Vehicle fitment provided in this listing is to be used as a rough guide only and may not actually suit your vehicle. Due to multiple brake packages sometimes being offered by manufacturers it may be necessary to measure your existing brake discs and or pads and compare with the measurements provided by DBA here: DBA Part Finder Click "Part Number Search" tab and input SKU provided above. Returns Exchanges will incur restocking and freight fees or may be denied in certain circumstances. The 4000XS is a premium cross drilled and slotted pattern designed to work in conjunction with DBA's patented Kangaroo Paw ventilation system. The XS pattern increases the number of out gassing exit points to allow brake pad friction gasses to escape through. This increases the consistency and effectiveness of every brake stop. These rotors also feature DBA's proprietary XG 150 high carbon alloyed iron and Thermal Stability Profiling (TSP) which prolongs the service life of the rotor. DBA's revolutionary universal drill and slot design eliminates the need for separate left and right slot designs seen in traditional rotor designs. For the spirited driver or performance modified street vehicle, the XS cross drilled and slotted design is the best option. Features (Where Applicable): Kangaroo Paw 144 diamond and tear drop pillar ventilation system Increased surface area resulting in greater heat dissipation which minimises brake fade and increases braking effectiveness and prolongs service life for both pads and rotors. Reduces mechanical damage and associated costs XS precision CNC machined slots and cross drilling Increased number of out gassing exit points for brake pad friction gasses to escape through increases the consistency and effectiveness of every brake stop. Universal drill and slot design eliminates the need for left and right discs XG150 High Carbon Alloyed Iron An increase in thermal capacity property allows the rotor to handle constant extremes of heat over extended periods of time which minimises warping and cracking and prolongs the service life of the rotor. Special formulation designed to respond to DBA's TSP process. Thermographic Temperature Monitoring Heat paint markings change colour at specific temperature thresholds offers the driver a clear indication of peak braking temperatures. When temperature thresholds are exceeded paint markings will permanently change colours allowing the driver to monitor rotor fatigue and decide on rotor replacement and to assist resellers with warranty claims. Paint protection on non friction areas Reduces corrosion, enhances appearance, stops any unsightly rust formation, adds value to the product.