400 is only bad if you try to print a super large picture because of some noise but its not bad.
for those of you who > me
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good stuff thanks guys 
You're not getting noise at 400. Lower ISO only works so well with noise, there's a limit as to the effect. The general rule of thumb is that you're OK up to 640 with most modern sensors before you get any noise with consumer rigs and 1000 with pro rigs.
i have noticed a little bit of noise at 400 but it was only in a darker situation than the track.
heading out to the track today for a little practice