We were using 3W-100's on a UAV I was working with last year that also incorporated the scoop. In the stock configuration it was mounted in reverse like in the picture in the first post. Just for the heck of it I turned one around one day for a flight and the telemetry noted a little over a 100 rpm increase from what all the other engines would turn. I'm npt going to say it's an absolute, but there were no problems with the fuel system and there was no other possible explanation for the increase in rpm.