Figure this is a teenager. I have one of these at home or rather did. These same questions always come up. Seriously though, a 1000 watt amp is not a huge drain. I run ~2500 watts in my car total. stock 80 amp alternator, sears Diehard Platinum battery. I have dimming but no other issues. Music does not pull amperage continuously. I have amp clamped my system and on tones I have pulled 138 amps. On music at full volume it never got above 110 amps draw.
My son also had a 1000 watt class D sundown audio amp. on a Mazda 3 hatchback. Stock electrical. Can show the install log. No issues.
So I figure, unless the OP has an old electrical system or components are weak, he should be fine.