My most infamous test results, back from the Great Bin In The Sky. Enjoy. Keep any replies clean & on topic.

The Test System:

1x Ford Festiva Trio
1x JBL W15GTi subwoofer (DVC 6ohm, wired for 3ohm)
Street enclosure tuned to 48hz
1x JBL A1201GTi 1200WRMS Monoblock
2x SuperCharge Gold 900CCA batteries
1x Stock 60A alt.
1x 0g wiring harness
1x Lightening Audio Competition Series 1.0 Farad Cap
1x Alpine headunit (5V subout, unclipped)

Test Equipment:
1x DMM
1x Goldline DSP-30 RTA

Test Method:
Amp hooked up to CRO, gains adjusted @ 60hz until clipping, then backed off. LP Xovers set to 80hz using CRO & DMM.
Enclosure strapped Street Beater style, ports blocked by tail gate, filler pack in wheel well and false floor installed (this gear is normally removed for SPL).
Engine idling @ 800RPM. Tests run with voltage on amp terminals showing @ 14.1V idle.
15 minutes cool down between runs.
Run some tones, find the "mad note" @ 51hz and commence testing.

(Quick Note: This system doesn't suffer from typical power issues such as blinking headlamps at night.. its a stout power supply)

No Rear Battery, No Capacitor.
Voltage On Burp: 12.8V (1.3V Drop)
Output: 140.7dB, 140.7dB, 140.6dB

No Rear Battery, 1 Capacitor.
Voltage On Burp: 12.6V (1.5V Drop)
Output: 140.5dB, 140.4dB, 140.3dB

Both Batteries, No Capacitor.
Voltage On Burp: 13.8V (0.3V Drop)
Output: 141.0dB, 141.0dB, 140.9dB

Both Batteries, 1 Capacitor.
Voltage On Burp: 13.2V (1.2V Drop)
Output: 141.0dB, 141.0dB, 140.9dB

seems abit inconclusive???

Both batteries with and without the cap both had the same output SPL?! But with the cap connected there was more voltage drop (probably due to the cap being instantly discharged at the start of the burp, then re-charged during the burp)?!

Yeh, its inconclusive, thats the point... caps are supposed to make things better