.15g per kilowatt.
Doesn’t seem that much for a 1000 watts. Thats’s like about 1.3 horsepower.
It is huge since it is reactionless thrust. Hook a plutonium reactor to it, pump in a few hundred or thousand kilowatts and the speeds you can achieve are astronomical. Things like to Mars in a week. To Jupiter in a week and a half. To Pluto in 2 weeks.