My M104 is fitted with mechanical CSI injection (Bosch KE). Later M104s had the electronic system.

Thus, DIFFERENT INJECTORS.

You need to specify.

In my case, the injectors have injected for nearly 360K Kms and seem to be doing fine (excellent performance and 30 mpg). If you really feel they need to be replaced, the part number is A0000785823 and list price in UK is about £50 each. Discounts are usually available.

You need to replace the seals and no calibration is possible or required.

RayH