My 0.02 is that radios are an un-necessary expence that unless you are in the top three aren't going to gain you more than a few seconds at each pit, at best. Added weight and complexity of using radios creates more distraction than positive effect. SCORE and BITD allows radio use, some like AMA does not allow radio use. What series are you racing?
"I couldn't wait for success, so I went ahead without it."