PROMYS and RSI

Hello,

I am a current sophomore planning on applying to RSI next year. I live in one of the most competitive states. By the time I apply, I will have taken some very advanced college (pure) math classes, and done a bit of research. I hope to attend PROMYS this summer. My question is: how much would attending PROMYS help my RSI application, all else forgotten?

If it helps, I am a girl. Not URM.