by J Kraus
Since Monday when word came down of Pontiac’s demise, many articles have been written bemoaning the loss of the firm that brought forth the Firebird and the GTO. However, no one has mentioned possibly the most intriguing and unique feature that Pontiac ever offered to enthusiasts.
I speak of course of Option Code W-73: Vacuum Operated Exhaust. This option was available exclusively on the 1970 GTO (though some sources report that a few late-1969 models were so fitted.) It allowed the driver to select between ‘quiet’ and ‘not so quiet’ exhaust modes. To my knowledge, this was the first driver-selectable dual-mode exhaust ever offered on a production car.
In the ‘not so quiet’ mode, the back pressure was reduced and the volume increased by about 10 dB. I find this vastly preferable to more recent automatic systems that activate on the basis of throttle opening or load. Sometimes one wants to use full power without attracting undue attention. Unfortunately, the option was killed after only 233 units were so equipped after GM executives saw the introductory television commercial and were concerned that the option might encourage bad behaviour.
Here is the infamous television commercial used to launch the option during the Superbowl of American football on 11 January 1970. Watch as the driver reaches down to switch out of the quiet mode. Notice that this model has two under-dash knobs. The one to the right controls the operation of the external carburettor ‘Ram Air’ scoops. You may want to turn up the volume: