There are a few requests for more data output via UDP, but not specifically for what I feel is an omission.
Forza Motorsport already works reasonably well with Simhub. However the rev lights are not synced up as RPM varies from car to car. If redline limit was output as well, this could resolve the issue (as opposed to manually setting it for each car). I believe this is how it works with a couple of other sims like Assetto Corsa.