I really had eyes on the Spiuk helmet, but couldn't stomach the price tag. So I modified my Giro to get what I liked about the Spiuk (clean underside that goes along the back). I was inspired by T.J. Tollakson's homemade aero setup at NOLA 70.3. http://jayprasuhn.blogspot.com/2009/04/tj-tollaksons-new-race-setup-revealed.html
Notice the opening at the point on the end for any air that may make its way in there to escape.
Tools of the modifications: Duct tape, elec tape scissors, synthetic spongesNow to give it some test rides!