Whats up with all the sandabaggers hagning out in Cat 4 till they're old enough the race masters? You boys have had your fun, now its time to take of the training wheels and move up with the big boys. You two are entirely too talented to spend another day/week/race/month/season riding Cat 4. Besides, when you upgrade not only do you get your ass kicked, you also get to start later in the day, you get to race longer (sometimes) and there are fewer crashes.
So what's holding you back other than fear?