That's because you won't be locally faster than light. You may cover 4 light years in one, but only because those light years will be much smaller from your point of view. You'll never "feel" faster than light.
I think you may have misinterpreted what I said. I didn't claim that you'd feel like you were covering the distance faster than light. I was saying that as you go faster (relative to your destination), space contracts ahead of you so the distance becomes shorter than it would if you were moving slower.