How to do SuperSonic Sled in 18.5 Seconds or less. I've done it in 17.5 seconds but didn't get the video before I accidentally reset it.
Start by pressing Up, 1 and 2 at the same time. Keep an eye on your boosters... as soon as they run out, immediately hit 3. The moment 3 runs out then hit 4. You should have your camera facing forward so you know when to stop. Hit 5 (reverse boosters) AND brake at the same time when you're very close to the finish line.
You can use the chicken gun to make the sled lighter, and thus get better times. I've heard of people finishing in less time, but I haven't seen any video of it.
Intel i7 950
MSI GTX 460 1GB
12GB Triple-Channel Corsair Dominator DDR3
2x Corsair F40 SSDs in RAID 0