I imagine for you it's similar to here, where the upper category races rarely fill up. In the 3s our field limits are usually 100 or more, but registrations are typically around 60. The 5s races always fill up quickly and are usually sold out in pre-reg, and for popular races the 4s can fill up quickly too. There is a big stage race in San Dimas this weekend, and the 4s were filled up like a month ago. The 3s got close but were a few short before reg closed. The P/1 race actually filled up early because of a bunch of pro teams with full squads, but the 2s had plenty of openings.