Keep posts from main RSS feed but include in category RSS?

Is there a way to add a post that will keep it from being added to the main RSS feed, but still let it be shown in the category RSS feeds?

I have a lot of people already subscribed to my main RSS feed. I am going to start posting more to specific categories that not everyone already subscribed would really want to get. And going forward I want specific posts to be able to stand out (in the main rss feed) and for people to be able to follow just the categories they want. Make sense?

Thanks,
Janell