Listen to the new 2016 Ford Shelby GT350 Start and Rev - Naturally-Aspirated 5.2-liter flat-plane crankshaft V8 engine. You can momentarily hear when the exhaust valve/flap is closed and then the Ford rep puts it into performance/sport mode and it opens at about 0:16 of the video. http://www.automotiveaddicts.com/5362...