Using SystemJS in production without Traceur

I want to use SystemJS to dynamically import AMD modules as well as System.import() modules on an as-needed basis. I can, of course, include <script src="system.js"></script>, but I'm getting an error that Traceur is not defined. I deliberately do not want to include Traceur, or any other dependencies, to keep requests to a minimum. Is there a version of SystemJS that allows importing AMD and System.import calls in one, semi-lightweight script?