Use a larger steering wheel
Attach the ends of the rack farther out from centerline on the spindles. May not be an option, but if it is it will surely help.
If you are not using the full available travel of the rack as is then this is a great idea, if it is possible.
If the steering is already using full travel of the rack then you would loose turning radius by moving the attachment points on the spindles, so probably not a good idea.
Other than that I think someone sells a gear box that goes in the steering shaft to either speed up the ratio or slow it down depending on which way you install it. May or may not be a good idea or legal?
Is there a different factory rack that interchanges and has a different ratio?
Grigg