Porsche 914 Stock Muffler compared to Bursch Muffler 

This video offers a comparison of the sound quality from a stock muffler on a 2.0 914, versus the aftermarket Bursch muffler. In the driving example, the driver is not accelerating at maximum, rather, trying to demonstrate how, under moderate acceleration, both mufflers can be reasonably quiet, albeit louder than a modern car.