NOTE: see observations below about measured size of new squirters; the comments here are 6.0 mm may be erroneous
Squirters are specified by nozzle diameter and overall bore diameter.
Porsche sells two bore sizes of squirters (6.0mm and 6.6mm diameter), but apparently some 3.0 cases have an intermediate size squirter installed (mine were 6.27mm). If you have the intermediate size, you will need to drill out the case bore to accept the larger, 6.6mm squirter. I used a letter size "F" drill to do this. Nerve racking, but not difficult.
Discussion of piston squirters
here and
here. Good information, but occasionally sidetracked by various issues.