Re: Question about stiffening cap
If you were to wire the cap in series, instead of parallel, it is possible to pass enough current through it that you might blow it up.
Do not do this, of course. Besides the obvious issue of it blowing sky high, they contain PCB's and other hazardous materials that can give you cancer.
'65 VW Bus
(2) PG Ti 12's, (2) Aura Sound 8's, (2) SoundStream 6.5 coax, (2) Alpine Type-S 6x9's [rear fill], MBQ DSC1500.1D, RF 501X
'02 BMW 330xi (AWD coupe)
Harman/Kardon 12-speaker System Option - sounds good =)