It's doable, by for racing why bother? If you win and you're examined and they see this funky aftermarket chip setup with a switch on the side of the DME box, what are you gonna tell them - 'honest sir, see that switch with a sticker next to it that says stock? I would never flip it into performance mode when racing.
' Then again, if you never get examined, how would they ever know if you were running a chip or not? Half the guys out there are probably cheating with a chip already.