I have a Fisher and Paykal machine that has a ramp up feature on start up. I used it for a while when I first started on cpap but don't use it any more. It helped with the feeling of inrush.
I agree with Matt on the Neti pot. Sort of a crazy idea but the thing works wonders if you're plugged up. I've also found that I don't have as much sinus trouble since I started using cpap. I think it has to do with breathing humidified air all night. Might not make a difference for you if you're living near the coast.
Jerry
Confidence: The feeling you experience before you fully understand the situation