[Elecraft] K3 filter question

[Adi Andrei]

I have the 5 pole 2.7 filters for main and sub RX.
One filter offset is -.94, the other is -.81
In order to do diversity receive, I have to set them both to about -.88

My question is: what happens when you set a filter offset differently than the one specified (as in my case) ?
How is this supposed to  influence operation (normal as well as diversity mode) ?
How can things be improved, short of buying new filters?

Thank you,

Adi
2E0TTX