I used Mango to give a quick impression of the inflated values; but these also appear when viewing the images with SPM. The same DICOM file converted using the june2015 version shows identical values as the raw DICOM (with intensity in SPM expressed as Y = 1X), whereas a conversion using the oct2016 version yields inflated values (for instance; intensity Y = 35 X, where this number can go up to 500). This intensity factor is revealed also when using spm_vol to get v_b.pinfo, where the first value is the 'scaling' factor.

For some scans (like EPI series) the values are interpreted to go up to three million, where we used to have them around 1000/2000. For anatomies values rise to the hundreds of thousands. Of course these are relative values, and the data and unique number of integers remains the same. But we do wonder why suddenly this 'intensity scaling factor' is different between releases. We've used DICOM from two Philips scanners (releases 3.3 and 5.3), and both give us similar results. 

I will prepare an anonymous sample-DICOM with two converted nifti files to share.