no power

I installed kooks catless long tube headers on my dark horse, now i dont have power to the screen/dash, headlights wont turn on, and my key fob wont register, but you can see that it has power in other areas, as well i have a random 6 pin connection that idk where it goes to, o2 extension are...

Anyone else experience a slight drop in power at 6,000 RPM? I do see on dyno graphs online that torque does drop off at 6,000 RPM so maybe it's because of that? This is on a 6 speed MT trans.