See absolutly no reason you cannot do the test yourself. Standard service proceedure on early volkswagon diesels. Of course common sense has to be applied like battery at same level for length of time cranking each injector. Plus an accuratly calibrated small container. Used primarily to eliminate certain possibilities basically. Or set up five lines and injectors to spray into 5 separate containers simultainiously. You could do comparison by weight with really accurate scales I think but they used to use small calibrated vessels. An extra set of injector lines from a junker to enable good positioning of injectors or bare lines is a good ideal for this test. Also allows a bonus of visual checking of spray pattern of each injector as well if you wish. A container much like a test tube might be the best if spraying through the injectors as release is so strong. On the otherhand cannot see why you could not collect just from the open lines either and might just prove easier and certainly more accurate in general. That also does eliminate variences in pop pressures as a factor.