Arrange by exact file type (not just by kind) in OS X Lion
It sounds like you want to "sort" your files rather than "arrange" them.


In Finder open up the folder you would like to sort by kind (file type).
Click the Action button (gear icon).
Choose Show View Options.
Set Arrange By to None.
Set Sort By to Kind.


Your files can be sorted more specifically now. There are also a few other tricks to such as holding down the option key while selecting what you would like to sort by, which overrides grouping.