My Blazer came with a 105 amp alt too. I was running roughly 2200 watts on that alt with just an Optima yellow top up front and the Big 3 done in 0/1 ga wire and one of those RF 25 farad caps. I did this for about a year before I upgraded the alt and changed out the Yellow Top for a Kinetik 1800 up front and added the 2400 in the rear. I didn't have any issues with voltage that I can recall. The 105 amp alt is good enough for now, but the life of your alt will be cut short because of the increased demands on it from your system.