Reverse rotation units are special order and not returnable in case of mistaken orders.
Please make sure its the correct unit.
Pulsar PSR7975G Compact Reverse Rotation
Dual Ceramic ball bearing system provides optimal turbo response & better durability by reducing play in the shaft.
10 Blade G-Aero Billet Compressor Wheel with Extended Tapered Tip Technology
9 Blade G-Aero Inconel 713c Turbine Wheel
Anti-Surge ported-shroud compressor inlet, cover with integrated speed sensor port
SPEC
Compressor Wheel: 79*98mm
Turbine Wheel: 82*75mm
Compressor Inlet: 4″ Hose
Compressor Outlet: 3″
V-BandTurbine Inlet: 3″ 
Turbine Outlet: 3.5″ V-Band
Water Ports: -6AN
Oil Feed: Flange Required (Recommended size: -4AN Std T4 Flange Non-Restricted)
Oil Drain: -12AN(O-Ring sealed Flange Kit Incl’) 
It's strongly recommended to run water cooling to aid reliability (needed for warranty)