A zobel for a particular speaker is a basic part of the design of the crossover - the single most difficult part of loud speaker design! Dunlevy has forgotton more about crossover design than most designers will ever know, let alone the rest of us.
Leave your speakers alone. Home rolling of speakers is grand folley, and you can certainly change the sound but will you ever know if is actually better.
Best regards, Jud Barber - Joule Electra