D16Z6 ... the internals are what is diffrent ... (i.e. the pistons/rods/crankshaft) the complete head is a z6 head . with exception of the camshaft (wich has much better specs, comparible to the ZEX 59300 camshaft). If you look at the part #'s on some websites ... like for the dc sports stuff... the dx and z6 header are the same part #. What are ya running (Engine/ECU/Transmission/Car) ? And what are ya planning to do ?