At the peak of the muscle car era, the 1970 Pontiac GTO offered an innovative driver-controlled exhaust that boosted performance—and ruffled feathers.

The Vacuum Operated Exhaust (VOE), initiated by a stealthy pull on a dash-mounted control, activated flaps on both mufflers that bypassed the stock exhaust routing and opened the gates to twice the sound and improved air flow. In concert with the Pontiac Ram Air induction system, the VOE delivered additional, measurable power. But it was pulled from the options list almost immediately as GM conformed to legal requirements in several states. (That was the official reason anyway. Unofficially, it was doomed by internal politics).

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