What could be causing battery and brake dash lights to flutter briefly during acceleration AFTER all this work was done?

have your alternator checked..

First check the battery 12.6 volts terminals clean and tight? Next make sure the alternator is charging properly 13.2 -14.8 OK

Hi. Thank you so much for the responses. So, I've done some testing of the alternator and battery. I've also thoroughly cleaned all battery connections. all the tests I'm able to do with my Multimeter are showing that the battery and alternator are running perfectly. I should mention what I have for additional electronics: Alpine MRV-500 Amp powering a DVC 12" Alpine Type R Sub, wired for 2 ohms. A cigarette lighter power-bridge that is powering a total of 7 very small LED arrangements, one in each footwell, one under each seat, one in each door, and one in the center console. Upgraded HID Fog Lights, simple plug and play set up. Lastly, I wired blue LED strips as trunk my trunk lights. I turned EVERYTHING on, opened my trunk, ran my AC, lights, the works. It mever even dropped under 14 volts. It spiked appropriately when things like headlights were first turned on, then evened out appropriately. When Car is turned off, and the battery slowly drops back down to 12.6ish volts. My Satellite radio is acting funny as well. I'm not sure if it's a connected issue, but when I first turn the car on, it will acquire signal and work flawlessly. As soon as my RPMS raise above 2000ish, it flashes "acquiring" and will either float between that and working, or just go to a "no signal" display. Before I dropped the car off to service, I had all the lights and audio equipment all working flawlessly. My radio rarely flashed "acquiring". Back to the core issue of the brake and battery dash lights flickering..I drive around town a little and kept slowing, then accelerating rapidly in order to make the lights flicker, and it is exclusively happening only after 2500rpms. So...any thoughts? Im wondering if there is possibly a loose wire somewhere maybe? I don't know if that would cause anything, but tomorrow I plan on investigating my Sat Tuner's wiring a little more closely, specifically the grounds, harness, and antenna. Slightly unrelated, but I'm also applying some sound dampening to my trunk and relocating my Amplifier's ground in order to tidy up the trunk a bit. Thank you so much if you read this far lol. I really appreciate it!!

Hey did you ever find out what was wrong