[ICOM] Optional Filters??

[AD5VJ Bob]

Not sure how the filter scheme works on the Icoms.

I am looking a purchasing some optional filters for my IC-775.
I can purchase one 9Mhz or one 455Khz but not more at this time.

Right now it is a toss up between

9 MHz FILTER
FL-223: 1.9 kHz/-6 dB (SSB NAR.)

455 kHz FILTER
FL-222: 1.9 kHz/-6 dB (SSB NAR.) 

If I can only get one of the above -
Which is the better choice to make for the best selectivity, or do I have to have them both IF's if I get either.

Any ideas appreciated.

Tnx bob ad5vj