Why would you really want to. I just cleaned mine out today and it took all of 10 minutes. My boost switch is located on the fire wall. The banjo fitting is on the manifold. Cleaned out the lines, checked the switch and put it all back together. The drilled out fitting would not make any difference in what the actual pressure was. Easier to just make sure its all like its supposed to be.

Bill Rokaitis
1985 300 SD 151,430 miles