First off I just want to say I have no horse in the race here beyond a desire for the integrity of my industry to to be increased and maintained. I've never used Ram Air, but based upon what I do know, I believe the system has the potential to sufficiently clean supply lines in the hands of an able technician. But off the top of my head, there are at least two major problems with this system that cannot be overlooked, of course, assuming one's desire is to properly clean the whole system as any true professional would desire. First, it is not possible to properly and efficiently clean what is almost always the most contaminated portion of the system, the return air ducting (the typically unfiltered lines most often located in the ceiling). Two, it is not possible in any way to properly clean what is often the second most contaminated portion of the system, the supply air main line(s) (which in predominantly cold climates runs through the crawl space and feeds air to each supply line). It seems to me Ram Air is being sold as a method that is complete in its ability to clean all portions of a customers air system, and I couldn't disagree more. If anything, it could be a nice time saving addition to a more complete 'Push-Pull' set up, but even then I just don't see how it fits in practically. Especially considering the Ram Air method calls for the blower to be running in order to perform the cleaning (a whole other issue), and conflicts with the 'Push-Pull' method that calls for the furnace to be shut down, so you couldn't even save time by having two technicians working opposite sides of the system. The bottom line is this, there is no easy way around the hard work and dedication it takes to properly clean a system, and there is no other method of cleaning that can compare to the time tested and proven 'Push-Pull' method. If you choose to go the route of Ram Air then be up front with your customers about the limitations of the process. Don't pretend your cleaning the whole system when your not, you'll sleep better at night.