Originally posted by SupraKid
If your peak voltage is below 13.5V in your first test, then your wiring is probably weak and should be upgraded, or you left hte tunes cranked for too long before you started your test. Your amp is choking on what you can feed it through the wire that you've run. Of course this assumes that your charging system is working properly int he first place. In my case, 13.8V -- Not a problem.

If the peak voltage is lower in the second test than it is in the first test, your amps are drawing more current than your electrical system can provide. Some drop might be expected, but anything noticeable indicates that your electrical system is overloaded. (This is why keeping the engine at or slightly below highway cruising RPM is needed -- to gauge how effective the alternator is.) Again, in my case, 13.8V -- Not a problem.

In either of these cases, a capacitor will be of no use to you,