I am definitely not on board with that, however I know that performanceproducts.com ran a filter magnet that was shaped kind of like a ring that would slip on to the outside of the filter and trap stuff that way. I would buy and use one of those if they were cheaper. IIRC they were like 120 bucks....
Here it is, they dont claim hp increase or mpg increase, just filtration....
http://www.filtermag.com/index.php