Normally I only go beyond grade 1 when I'm running a downsized pp to get the extra jump range from saving weight. Some very good rolls like yours are possible on grade 1. Interestingly, armoured power plants can get a weight reduction and increased power capacity as secondary effects, so if I just want a little extra power without going overcharged and don't mind a bit of weight, then rolling a few of those can give me what I need.