Trust what you know and avoid what doesn't work for you. You've probably been training for this for some time, so you should have an idea what your GI can tolerate and what it can't.

If this is my "A" race I'd be in taper and cut my caloric intake down to maintenance levels and eat nutrient enriched foods, IE, salmon, almonds, lots of green veggies, and whole grains. I stay clear of beef and dairy just because my tummy has a hard time digesting. 3 days before the race I up my caloric intake to that of training level and focus more on foods with higher sodium and potassium levels...that way my body has had a chance to get used to the bloating feeling before race day - and it keeps me hydrated.

I'd probably suggest staying away from high fiber foods the day or two before race day if your not used to them. On race day you want to go but don't need other things going :) If your prone to upper GI issues stay away from acidic foods, tomatoes, coffee, dairy, artificial sweetners and so on.