Why does a flat-plane Ferrari V8 scream while a cross-plane V8 burbles at similar RPMs?

Answer: Because flat-plane cranks send evenly spaced pulses into each exhaust bank.

Because flat-plane cranks allow a higher redline, which alone sharpens the pitch. — Not quite. Higher rpm does raise pitch, and flat-plane V8s often rev higher, but the question holds rpm roughly constant. At the same rpm, the scream comes from how evenly the exhaust pulses are spaced, not from a higher redline. Redline sets a ceiling, not the timbre heard at a given engine speed.

Because flat-plane cranks send evenly spaced pulses into each exhaust bank. ✓ — Right. A flat-plane crank alternates firing more evenly between the two cylinder banks, so exhaust pulses arrive in a regular sequence at each bank. That regular pulse train favors a sharp scream instead of the uneven burble tied to many cross-plane V8s. Ferrari also tunes exhaust geometry and valves, but the core difference is the rhythm of the pulses.

Because open exhaust tips add a sharper resonance to every V8 engine. — Not quite. Open exhaust tips can make any V8 louder and less filtered, so they can exaggerate treble. But they cannot create the even pulse pattern that a flat-plane crank produces. If the exhaust pulses arrive unevenly, open tips mostly expose that unevenness rather than smoothing it into a scream.