The CB1100 Community Forum

K&N Does make a filter for the CB1100 DLX. From K&N's Website - Part Numbers:
KN-204 (Black) for $15.49
KN-204C (Chrome) for $18.79 (The chrome ones were recently on sale on Amazon for $9.06/each, less than half-price)

You can get oem filters online for about 1/2 that price $9 each buying a 3 pack. I buy two 3 packs at a time. Lasts me 1 riding season for my 2 bikes.