A common misconception - you can purchase a small lock to lock turn-count gearbox, labeled "fast-ratio", and you'll have responsive steering.
The table below identifies two gearboxes with the same lock to lock numbers to illustrate the issue. Gearbox number 1 is a true fast ratio gearbox with a small lock to lock number. Gearbox number 2 is a slow ratio gearbox with large internal stops, (the stops are creating the small lock to lock number.) Not all gearboxes use internal stops, but many do. If they aren't appropriate for your vehicle, they will increase your turning radius.
Gearbox no. 2 will have unresponsive steering and require a larger turning radius when parking or making a u-turn. It will lead to disappointment. Make sure you understand the details when purchasing a fast ratio gearbox, lock to lock numbers alone don't tell the full story.