Overriding ImageMagick transformer for image/x-dwg

[mycroes]

I created a (complex content-)transformer to convert DWG files to PNG images using PDF files as intermediate file format. However, when I request the PNG transformation Alfresco will choose ImageMagick over my own transformer. In debug output it does list my transformer:

15:02:08,993 DEBUG [org.alfresco.repo.content.transform.ContentTransformerRegistry] Searched for transformer: 
   source mimetype: image/x-dwg
   target mimetype: image/png
   transformers: [ProxyContentTransformer[ average=0ms], ComplexContentTransformer[ average=0ms]]‍‍‍‍

However, it uses ImageMagick as transformer. Is there any way I can specify priority (perhaps an option to influence the reliability factor)?
Regards,

Michael

[mycroes]

Seems in the end my own content transformer gets used after all (as in after a while), however the log does spit some errors because ImageMagick can't convert the file. It would probably be nice if this wouldn't happen, because it also affects the ImageMagick reliabilty number negatively, even though it's expected that ImageMagick can't cope with the DWG file.
Regards,

Michael