Radios are legal in WKA “Road Racing”, and we have used them for many years. Instant feedback to the driver, and questions from driver to pit. Used mainly for splits to following karts, how many karts are running in your karts group (sometimes you can’t tell), etc.
We were very pleased with our Racing Electronics/Motorola units. A little pricey at $1900!
BUT, just this year we stopped using them. It’s just one more thing you DON’T have to mess with.