I have a Alpine pdx 1000.1 and a pdx 4.150 amp and a w7 with a 2.5 farad capacitor and 0 gauge wire hooker up to a anl 250 amp fuse and my light dont dim and i have a 90 amp alternator. I use to have a t40001bd hooked up with the same alternator and power wire with no problems . . . it was just to freakin' big.
Hope this helps
My head unit is a D3 and with the radio up i never see less than 13.1 volts from the head unit.