[deanh74_2]

Originally Posted by Nathan Acree You could then run an exhaust clip of an Opel with an open exhaust revving through a specified RPM band (i.e no muffler to get the engines raw sound), run that through an FFT to get the frequency and amplitude components through that RPM band and then run that through a linear phase digital filter based on the mufflers frequency response and transform that back to the time domain. The result would be how an Opel would sound using that particular muffler (there other effects that would be difficult to quantify- like the effects of standing waves and backpressure etc). However, muffler manufacturers seem unwilling to share this information; I have asked a few, and the response is that that information is proprietary. I suspect that most manufactures don't even do a thorough analysis of their products frequency response. Flowmaster and MAC do this, but they will not share the data. Nathan Acree Albuquerque New Mexico

AAHHH.... Yea what he said...