I am replacing a 1000D with the SAZ-1500D. I already have 4 gauge power and ground run to the trunk. Will I experience significant loss by using 4 gauge? I will be running the amp at 1ohm.

4 gauge ground is about 24" long going into a ground distro block with 0 gauge grounded from the block to the chassis about 12" away.

Existing 4 gauge power is about 3 feet from a distro block that has 0 gauge coming to it from the battery.

I have done the big 3 with 0 gauge. Have a 200A alt as well.

Lastly, will a 150A fuse be enough for the 1500D?

Thanks all.

If you already have 1/0 coming from the front of the car and you are only running a few feet of 4awg, i'd say your straight, but some people may disagree. as far as the fuse, i would imagine sundown has a recommendation somewhere in the product literature. just remember that amps x volts equals watts, so figure 14 volts x 150 amps = 2100 watts, now assume that you will be at roughly 75 percent efficiency @ 1 ohm, maybe a hair less. So 75 percent of 2100 is 1575 watts. Unless you are burping or doing something that draws peak power from the amp, which most music won't do, i'd say 150 will be fine, maybe step it up a notch if you are competing. i'm tired and my math may be retarded right now. just wait for jake to answer

The small run of 4 awg is fine.