Fastslappy is correct here.
Bob's networks will give you back stock or better performance with aging network caps that may or may not have high ESR. The caps should be better than stock.
But don't think for a minute that you can't go beyond the stock performance. IMO you get what you pay for!
If you's like better bass IMO buy the largest Air Core Inductor you can afford. You could mount it on a side wall if you had to or the bottom of the cabinet. IMO Iron Core Inductors compress the sound and take warmth from it.
You'd be surprise how far you can go, of course it is system dependent other componets of the system should be good to make it really worth while.
No Regrets and I have spent more than my speakers cost new!
http://www.northcreekmusic.com/COILS.html
SET12 :thmbsp: