B & W 801 S3 Crossover Upgrade

Hello fellow Goners!! I originally posted earlier an inquiry if anybody knows if North Creek Music Systems are still in business. I think I’m going with they are no longer in existence. If anyone knows different, please post your input here. Are there any diy’ers who have either upgraded their own crossovers that would be willing to share the recipe or going one step further, anyone have blueprints/schematics to the North Creek Ultimate or Junior upgrade recipe? Thank you in advance.