i've never raced my car on a real track, but for autox and aggressive street driving stock sized brakes are fine from my experiences. there's no need to go bigger right off the bat. add some good fluid and decent pads and they'll be plenty. you won't run into fade problems on such a short track at such low speeds. for an open road course i'm sure they could use some improvement, but for the OP it's not something he's going to need immediately.
also, i was assuming that the car in question would be the 2000 ss mentioned in the OP's sig
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|2000 Trans Am|T56 swap|Bolt Ons| Suspension|
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