How do you swap the ignition wire loom boot?

[661300]

1987 325IS

Installing a new set of spark plug wires and the new STI wire set does not have the rubber boot that is between the plastic rail and the distributor end of the wires. Can you swap the old boot with out cutting it?

[BMWManiac]

The OEM wires are contained within the plastic rail and the rail can be separated apart....you should be able to remove the boot from it, but I'm not sure if it will fit over the other end that plugs into the cap