The D while in the engine code means dual overhead camshaft (DOHC). This is often achieved by fitting an RB25DE or RB26DETT cylinder head and or turbo to a standard RB30E/T block. The RB25DET just isn't usually used.HKS has also produced a new camshaft placement sensor with a flush anodized mount, offering the engine a signature look.Even so, you m