Is there anything wired to the truck that could be drawing too much current right after startups like an amp or trailer brake module or lights etc.?

I have a 1200 watt RMS amp in my truck, and if I cut it up loud right after startup, before the thirty seconds or so delay before I get 14 volts.

I have thrown it in battery saver mode. Just a thought, but maybe some parasitic draw can be tricking the computer.