To full maximize the blower one must remove the back end and pull the bag out that collects all the debris to maximize the airflow getting sucked in. For the first 2 seconds blow it away from the vehicle to flush out the hoses but thats all you need.
The metro vac is a great vacuum but one thing that doesn't get mentioned with all of its hype is that its not a wet dry vac. I've had one for a little less than a year and if you do carpets that have had drink spills recently or are still slightly wet from when you clean carpets or any other moisture standing and you need to do a quick vac before leaving, then that moisture can harm your vac. Mines messed up already and its not even a year old! There are a few really good wet dry shop vacs out there that have the same or higher water lift as the metro vac and they are about in the same price range if not cheaper too. Yes it would be nice to have the blower feature, but in the long run I think you'll find out quickly that you'll really be wishing you had bought a wet dry vac just as powerful as the metro instead