Large throttle bodies can provide for a boost in performance, without any head or intake work. Evidence of this can be seen in the Mustang and various bow-tie engines. However, the gain is usually pretty marginal on throttle body upgrades without additional work (in the realm of 3-5HP). 99-04 Mustangs have been known to net a 13HP gain in replacing the throttle body and the upper plenum elbow (the cast intake tube between the throttle body and intake). But that 13HP comes at a cost of around $400+, and we sure are not driving mustangs!
And as Quik said... doubtful it was truly bored out. Usually the only real way to get significant dimensional gains is through an entirely new casting. It might have been polished; but that's virtually useless...