Just so you know, neither a huge flat 360 (and I mean honkin' huge) nor a backflip-Superman-seatgrab-Indian-air-combo will bring home gold at least not anymore. To win these days you must now perform a seat grab/body varial 360.
To do this take the 45-foot super kicker, not the short ramp because you're going to need the hang time. Once in the air move into a simple seat grab but then spin your body 360 degrees keeping parallel to the ground rushing below you. On successful completion of your spin, grab the bike and pull yourself back on the seat as you will have only a few nanoseconds to land the trick properly.
With proper speed and kick off the ramp you should have about three seconds to perform this.