Question

is it possible to go 335,000,000 mph? (or half the speed of light)

Answer 1

Yes, it possible. Electrons, protons can achieve speeds which close to speed of light. Physical limit is the speed of light, not half the speed of light. If you mean massive object it seems to be impossible on current technology level. But in ideal situation, when you have “good” engine, it possible for massive object too.