Thanks for the replies guys. I use my computer for pacing in practice. When riding in the aero position at 28 mph it doesn't feel much different than 30 mph, however the end result is significant. If I have someone calling out lap splits I'll be able to speed up or ease up to maintain my target power and cadence. In my 6 lap race I believe that laps 2 - 4.5 are critical in maintaing my perferred pace. If I drift down to 28 mph for laps 3 and 4 I will have lost time that I can't make up.