So i used the default css & js minify of latest version of osclass and got very good score on gtmetrix.

Then i activated the keycdn (using your plugin) and got worst score, seems like it loaded all the files a seperated it again, not minified.

How can i make them work together? So the cdn will load the minified files?

 Do you have showcase of this somewhere?
CDN plugin update resources URLs to point to CDN server, does not modify/add styles or scripts (at least it should not)