push to talk systems

[moab mark]

Has anybody had any success with the fm radio/throat mic/remote mic systems while riding? Trying to find something that works to be able to tell my 8 year old to slow down. The basic motorola fm with the little headset mic system will not communicate clear enough at speed. Any ideas? There are some systems out there for around $300 but trying not to spend that kind of coin. If you spend the coin do they work?

Mark