Seimens builds injectors for OE applications, they are also excellent injectors. So are Bosch, Denso, and Delphi (which are all OE suppliers). OEM applications have to be finely matched in flow rate in order to pass emissions tests required of new cars, and they're expected to last at least 100,000 miles (till the warranty is up at the very least). They also have the most R&D money to spend because they're constantly raking it from all the car manufacturers that buy their injectors by the millions.