"Letting her rip" is a colloquial expression that refers to allowing someone or something to go at full speed or intensity. This phrase is often used to describe a fast-moving vehicle or a strong emotion. If you are looking for alternatives to the phrase "letting her rip," you could use "giving it all you've got," "exerting maximum effort," "unleashing," or "seizing the moment." Another similar phrase you could use is "going full throttle." These synonyms convey the same sense of excitement, energy, and urgency as "letting her rip" and can be used in a variety of contexts.