Hmmm thats a good question, but i'll tell you this...
I'm running a 460x1 watts RMS for my sub, as well as a 50x4 watts RMS for the interior, so I guess thats 660 RMS worth of power...
I'm running off the stock alternator fine, although I'm using 4 gauge power AND ground cables. I have a distribution block in the trunk that splits the 4 gauge power cable coming from the battery to 8 ga wires to the amps.
A couple months after the initial install, I used whatever excess 4 gauge wire to make new ground wires for the battery and valve cover. This made a suprisingly big difference in bass richness, fullness, and overall sound. My headlights dimmed less when I pushed up the volume.
Its been a little under a year since I did the first stage of the install (amp and sub), and i've never experienced a battery failure.
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DB Squad
Integra Forum Moderator
2016 BMW 340i M-Sport / 2013 Chevrolet Volt / 1999 Subaru Impreza RS EJ205