Sorry, meant to say they are a direct physical replacement, same dia O rings and same length. They obviously flow a lot more than standard injectors. I will be using an Omex 710 hence the need for high impedance injectors, not much available from Bosch - the Siemens Deka items listed are a good price but probably over capacity for what I need. This will not be a problem as long as idle/low speed performance is ok, and plenty of scope to increase power in the future if req.