Well what the lab says is normal is often well below optimal for a male. 250ng/dL for example is considered within range but is a 5th of what healthy young men had 75 years ago. The ideal I would say would be in the low 1000s, but probably not worth hopping on T if you're not below 500. One option you can do without shutting down natural production is taking HCG or clomid or both which is what many clinics will do for hypogonadal men under age 25.