[z12358]

Originally Posted by noone986s

I have been looking at ordering one of these

http://cgi.ebay.co.uk/Porsche-Boxster986S-3-2-986-Sport-Sound-Muffler-Exhaust_W0QQitemZ290056062535QQihZ019QQcategoryZ38 786QQcmdZViewItem

Might be a different way of installing the valve in the bypass pipe. The video shows what effect the bypass has.

The Box on that video sounded like crap.

I feel many people are not really familiar with what goes into designing a complex acoustic system such as the exhaust. It has been years, but I remember how in high school Acoustics, we used to build Acoustic curcuits equivalent to electric curcuits. The idea was that the formulas describing the physics (dynamics) of sound waves (air pressure) in enclosed spaces are equivalent to the math describing the current in passive electric RLC (resistor, inductor, capacitor) circuits.

That math is not simple, and far from straightforward. You take one resistor out of an electric circuit and the circuit will stop doing what it was meant to be doing. There are issues of frequency bands and filters, harmonics distortion, and resonance. When all that gets combined with the physics of the car that surrounds the system, it gets even more complicated. Pockets of resonance (amplification of a certain frequency band) can fall right on top of the frequency bands defining the car's structure and rigidity -- and that's when the whole car starts shaking at certain rpms.

I doubt that ANY of the after market exhaust vendors has modeled any of these things the way I'm sure Porsche has.

My point is, these exhaust mods are not trivial, and sound level is not even close to being the most important factor to consider.

Z.