Before I was using the original Mazda 6 air Filter and it suffered from smooth acceleration and low-end to top-end power.  Now using the K&N Panel filter for Mazda 6 - On the highway sprint and the acceleration from the new kn filter 33-2278 will noticeably improve though out out the gear change especially at passing speeds. K&N filter will also significantly  improved my fuel efficiency!

Part 33-2278 Filter Specifications
Height: 1 in (25 mm)
Outside Length: 12.625 in (321 mm)
Outside Width: 6.875 in (175 mm)
Weight: 0.99 lb (0.45 kg)

33-2278 Cross Reference
AC Delco A2050C
BMC FB38304
Champ Labs. AF7953
Fram CA8922
Luber-Finer AF7953
Mann-Hummel C3233
Mazda RF4F13Z40
Mazda RF4F13Z409A
Mazda RF4R13Z40
Mazda RF4RF13Z40
Mazda RF7F13Z40
Mazda RFZA13Z40A9U
MicroGard MGA42825
MicroGard MGA49114
Mobil MA5370
Premium Guard PA5370
Purepro A5370
Purolator A35370
Ryco A1429
Service Champ AF5370
Simota OMA001
STP SA8922
Valvoline VA190
Warner WAF7953
Wesfil WA1061
WIX 42825
WIX 49114
K&N 33-2177-1, is also very close to this filter listed 33-2278

The Official K&N website reads it fits the following Vehicles:
2012 Mazda Atenza 2.5L L4 Gas
2012 Mazda 6 2.0L L4 Gas
2012 Mazda 6 1.8L L4 Gas
2011 Mazda Atenza 2.5L L4 Gas
2011 Mazda Atenza 2.3L L4 Gas
2011 Mazda Atenza 2.0L L4 Gas
2011 Mazda 6 2.0L L4 Gas
2011 Mazda 6 1.8L L4 Gas
2010 Mazda Atenza 2.5L L4 Gas
2010 Mazda Atenza 2.3L L4 Gas
2010 Mazda Atenza 2.0L L4 Gas
2010 Mazda 6 2.5L L4 Gas, Non-US Models
2010 Mazda 6 2.2L L4 Diesel
2010 Mazda 6 2.0L L4 Gas
2010 Mazda 6 1.8L L4 Gas
2009 Mazda FAW Ruiyi 2.5L L4 Gas
2009 Mazda FAW Ruiyi 2.0L L4 Gas
2009 Mazda Atenza 2.5L L4 Gas
2009 Mazda Atenza 2.3L L4 Gas
2009 Mazda Atenza 2.0L L4 Gas
2009 Mazda 6 2.5L L4 Gas, Non-US Models
2009 Mazda 6 2.2L L4 Diesel
2009 Mazda 6 2.0L L4 Gas
2009 Mazda 6 2.0L L4 Diesel
2009 Mazda 6 1.8L L4 Gas
2009 FAW Pentium B50 1.6L L4 Gas
2008 Mazda Atenza 2.5L L4 Gas
2008 Mazda Atenza 2.3L L4 Gas
2008 Mazda Atenza 2.0L L4 Gas
2008 Mazda 6 2.5L L4 Gas
2008 Mazda 6 2.3L L4 Gas, US Models Only
2008 Mazda 6 2.0L L4 Gas
2008 Mazda 6 2.0L L4 Diesel
2008 Mazda 6 1.8L L4 Gas
2007 Mazda Atenza 2.3L L4 Gas, Except Turbo
2007 Mazda Atenza 2.0L L4 Gas
2007 Mazda 6 2.5L L4 Gas
2007 Mazda 6 2.3L L4 Gas
2007 Mazda 6 2.0L L4 Gas
2007 Mazda 6 2.0L L4 Diesel
2007 Mazda 6 1.8L L4 Gas
2006 Mazda MPV 3.0L V6 Gas
2006 Mazda MPV 3.0L V6 Gas, China
2006 Mazda MPV 2.3L L4 Gas
2006 Mazda MPV 2.0L L4 Diesel
2006 Mazda Atenza 2.3L L4 Gas, Except Turbo
2006 Mazda Atenza 2.0L L4 Gas
2006 Mazda 6 2.3L L4 Gas
2006 Mazda 6 2.0L L4 Gas
2006 Mazda 6 2.0L L4 Diesel
2006 Mazda 6 1.8L L4 Gas
2006 FAW Pentium B70 2.3L L4 Gas
2006 FAW Pentium B70 2.0L L4 Gas
2005 Mazda MPV 3.0L V6 Gas
2005 Mazda MPV 3.0L V6 Gas, China
2005 Mazda MPV 2.3L L4 Gas
2005 Mazda MPV 2.0L L4 Diesel, China
2005 Mazda Atenza 2.3L L4 Gas, Except Turbo
2005 Mazda Atenza 2.0L L4 Gas
2005 Mazda 6 2.3L L4 Gas
2005 Mazda 6 2.0L L4 Gas
2005 Mazda 6 2.0L L4 Diesel
2005 Mazda 6 1.8L L4 Gas
2004 Mazda MPV 3.0L V6 Gas
2004 Mazda MPV 3.0L V6 Gas
2004 Mazda MPV 2.3L L4 Gas
2004 Mazda MPV 2.0L L4 Diesel
2004 Mazda Atenza 2.3L L4 Gas
2004 Mazda Atenza 2.0L L4 Gas
2004 Mazda 6 2.3L L4 Gas
2004 Mazda 6 2.3L L4 Gas
2004 Mazda 6 2.0L L4 Gas
2004 Mazda 6 2.0L L4 Diesel
2004 Mazda 6 1.8L L4 Gas
2003 Mazda MPV 3.0L V6 Gas
2003 Mazda MPV 2.3L L4 Gas
2003 Mazda MPV 2.0L L4 Diesel
2003 Mazda FAW 6 2.3L L4 Gas
2003 Mazda FAW 6 2.0L L4 Gas
2003 Mazda Atenza 2.3L L4 Gas
2003 Mazda Atenza 2.0L L4 Gas
2003 Mazda 6 2.3L L4 Gas
2003 Mazda 6 2.3L L4 Gas
2003 Mazda 6 2.0L L4 Gas
2003 Mazda 6 2.0L L4 Diesel
2003 Mazda 6 1.8L L4 Gas
2002 Mazda MPV 3.0L V6 Gas, China
2002 Mazda MPV 2.3L L4 Gas
2002 Mazda MPV 2.0L L4 Diesel
2002 Mazda Atenza 2.3L L4 Gas
2002 Mazda Atenza 2.0L L4 Gas
2002 Mazda 6 2.3L L4 Gas
2002 Mazda 6 2.0L L4 Gas
2002 Mazda 6 2.0L L4 Diesel
2002 Mazda 6 1.8L L4 Gas

Mazda 6 Performance Oil Filters
OEM Replacement Oil Filters for Grand Vitara
Heavy Duty Construction
High Flow Rate
Outstanding Oil Filtration
Canister Types have Exposed Nut Designed for Easy Removal
Works Great with Synthetic Oil

HP-1002
2012 MAZDA 6 2.5L L4 F/I - All
2011 MAZDA 6 2.5L L4 F/I - All
2010 MAZDA 6 2.5L L4 F/I - All
2009 MAZDA 6 2.5L L4 F/I - All

HP-1008
2002 MAZDA 626 2.0L L4 F/I - All
2002 MAZDA 626 V 2.0L L4 F/I - All
2001 MAZDA 626 2.0L L4 F/I - All
2001 MAZDA 626 V 2.0L L4 F/I - All
2000 MAZDA 626 2.0L L4 F/I - All
2000 MAZDA 626 V 2.0L L4 F/I - All
1999 MAZDA 626 2.0L L4 F/I - All

HP-2009
2012 MAZDA 6 3.7L V6 F/I - All
2011 MAZDA 6 3.7L V6 F/I - All
2010 MAZDA 6 3.7L V6 F/I - All
2009 MAZDA 6 3.7L V6 F/I -All

HP-2010
2008 MAZDA 6 3.0L V6 F/I - All
2007 MAZDA 6 3.0L V6 F/I - All
2006 MAZDA 6 3.0L V6 F/I - All
2005 MAZDA 6 3.0L V6 F/I - All
2004 MAZDA 6 3.0L V6 F/I - All
2003 MAZDA 6 3.0L V6 F/I - All
2002 MAZDA 626 2.5L V6 F/I - All
2001 MAZDA 626 2.5L V6 F/I - All