Now I don't usually second guess application guides, but I noticed something strange for the m750: They used one filter until 1997, went to a new filter model for 97-98, then went back to the original filter for 1999+.

The DU-0900, according to their site is used for:

http://www.knfilterchargers.com/search/applications.aspx?Prod=DU-0900

K&N Applications for DU-0900

2002 DUCATI 900SS I.E. 900 - All

2001 DUCATI M600 MONSTER 600 - All

2001 DUCATI MONSTER M900 CROMO 900 - All

2000 DUCATI M600 MONSTER 600 - All

2000 DUCATI MONSTER M900 CROMO 900 - All

1999 DUCATI 600SS 600 - All

1999 DUCATI M600 MONSTER 600 - All

1998 DUCATI 600SS 600 - All

1998 DUCATI 750SS 750 - All

1998 DUCATI 900SS 900 - All

1998 DUCATI 900SS FE 900 - All

1998 DUCATI M600 MONSTER 600 - All

1998 DUCATI M750 MONSTER 750 - All

1998 DUCATI MONSTER 900 900 - All

1997 DUCATI 600SS 600 - All

1997 DUCATI 750SS 750 - All

1997 DUCATI 900 SUPERLIGHT 900 - All

1997 DUCATI 900SS 900 - All

1997 DUCATI M600 MONSTER 600 - All

1997 DUCATI M750 MONSTER 750 - All

1997 DUCATI MONSTER 900 900 - All

1996 DUCATI 600SS 600 - All

1996 DUCATI 750SS 750 - All

1996 DUCATI 900 SUPERLIGHT 900 - All

1996 DUCATI 900SS 900 - All

1996 DUCATI M600 MONSTER 600 - All

1996 DUCATI MONSTER 900 900 - All

1995 DUCATI 600SS 600 - All

1995 DUCATI 750SS 750 - All

1995 DUCATI 900 SUPERLIGHT 900 - All

1995 DUCATI 900SS 900 - All

1995 DUCATI M600 MONSTER 600 - All

1995 DUCATI MONSTER 900 900 - All

1994 DUCATI 600SS 600 - All

1994 DUCATI 750SS 750 - All

1994 DUCATI 900 SUPERLIGHT 900 - All

1994 DUCATI 900SS 900 - All

1994 DUCATI M600 MONSTER 600 - All

1994 DUCATI MONSTER 900 900 - All

1993 DUCATI 600SS 600 - All

1993 DUCATI 750SS 750 - All

1993 DUCATI 900 SUPERLIGHT 900 - All

1993 DUCATI 900SS 900 - All

1993 DUCATI M600 MONSTER 600 - All

1993 DUCATI MONSTER 900 900 - All

1992 DUCATI 600SS 600 - All

1992 DUCATI 750SS 750 - All

1992 DUCATI 900 SUPERLIGHT 900 - All

1992 DUCATI 900SS 900 - All

1991 DUCATI 600SS 600 - All

1991 DUCATI 750SS 750 - All

1991 DUCATI 900 SUPERLIGHT 900 - All

1991 DUCATI 900SS 900 - All

1988 DUCATI 750 PASO 750 - All

1987 DUCATI 750 PASO 750 - All

Then the DU-9098:

http://www.knfilterchargers.com/search/applications.aspx?Prod=DU-9098

K&N Applications for DU-9098

2004 DUCATI 1000SS 1000 - All

2004 DUCATI 800SS 800 - All

2004 DUCATI ST3 992 - All

2004 DUCATI ST4S 996 - inc. ABS

2003 DUCATI 1000SS 1000 - All

2003 DUCATI 620 SPORT 620 - All

2003 DUCATI 800 SPORT 800 - All

2003 DUCATI 800SS 800 - All

2003 DUCATI ST2 944 - All

2003 DUCATI ST4 916 - All

2003 DUCATI ST4S 996 - All

2002 DUCATI 750SS 750 - All

2002 DUCATI MONSTER 900 DARK I.E. 900 - All

2002 DUCATI MONSTER 900 I.E. 900 - All

2002 DUCATI ST2 944 - All

2002 DUCATI ST4 916 - All

2002 DUCATI ST4S 996 - All

2001 DUCATI 750 I.E. 750 - All

2001 DUCATI 900SS I.E. 900 - All

2001 DUCATI M750 MONSTER 750 - All

2001 DUCATI MONSTER 900 I.E. 900 - All

2001 DUCATI ST2 944 - All

2001 DUCATI ST4 916 - All

2001 DUCATI ST4S 996 - All

2000 DUCATI 750 I.E. 750 - All

2000 DUCATI 900SS I.E. 900 - All

2000 DUCATI M750 MONSTER 750 - All

2000 DUCATI MONSTER 750 DARK 750 - All

2000 DUCATI MONSTER 900 900 - All

2000 DUCATI MONSTER 900 I.E. 900 - All

2000 DUCATI MONSTER M900 DARK 900 - All

2000 DUCATI MONSTER M900 S 900 - All

2000 DUCATI ST2 944 - All

2000 DUCATI ST4 916 - All

1999 DUCATI 750SS 750 - All

1999 DUCATI 900SS 900 - All

1999 DUCATI M750 MONSTER 750 - All

1999 DUCATI MONSTER 750 DARK 750 - All

1999 DUCATI MONSTER 900 900 - All

1999 DUCATI MONSTER M900 CITY 900 - All

1999 DUCATI MONSTER M900 CROMO 900 - All

1999 DUCATI MONSTER M900 S 900 - All

1999 DUCATI ST2 944 - All

1999 DUCATI ST4 916 - All

1998 DUCATI ST2 944 - All

1997 DUCATI ST2 944 - All

1996 DUCATI M750 MONSTER 750 - All

At first glance everything looks good, 9098 for the newer ducs, 0900 fir the older. But look at the 9098 listed for a 1996 monster 750, 0900 for 1997-1998 monster 750, then back to 9098 for the 1999+ m750.

Did ducati really go from one filter, change for 2 years, then go back??