This instructional guide is only for ID1300's being used with T1 fuel rails in the R35 platform. If you are using stock fuel rails, this does not apply to you.
In this application there is a cast part on the cylinder head that limits the electrical connector from being able to go all the way on in cylinders 3 and 4.
Simply modifying the mating connector as shown will allow proper fitment and still allow a proper seal for the electrical connections. This only needs to be done on cylinders 3 and 4.