I agree that the Bongo is by far the worst GA transport for its occupants. Enough to make one’s ears bleed. Anything with Garretts is only as good as the internal soundproofing and engine location relative to the cockpit, which varies between airframe types - eg Conquest not too bad on the inside, but still noisy enough that too much exposure could damage hearing on the ramp.
Not GA, but anything with RR Darts made quite a nasty racket, too.