Posted for Walter Atkinson <walter@advancedpilot.com>:

FWIW, I ran a test.
 
 1) MP measured with NO FILTER AT ALL.
 
 2) MP measured with paper filter.
 
 3) MP measured with bracket filter
 
 4) MP measured with K&N filter.
 
 
 They resulted in the following order of MP, from highest to lowest:
 
 NO filter, PAPER filter, K&N filter, BRACKET filter.   The two middle ones
were very close to the same--frankly, too close to call as being any
different.
 
 YMMV.
 
 Walter