Thrilled.
Very frightening.
Involving a knee-trembler.
Overwhelmed.
Causing a feeling of rapture.
Terrified.
Impressive.
Excited.
Of an engine, a motor vehicle, etc.: modified for higher performance.
Intoxicated by alcohol or drugs.
Improved.
Of a racehorse: injected with a substance to make it run faster or to change its temperament.