on tatooine, the times to beat are SET. not like on Taris where no matter what time you you get, they have someone get better.
i know this cause my tier1 time was better than their tier2 record.
the couple times on tattooine should be close to 23sec, the last one 22 something.
like he said, just takes practice. Always be hitting a speed ramp, shift properly and don't hit any obstacles and you should be flyin.
i think my top time was just over 22sec, but it did take about 10 tries to get used to it and beat the whole thing.