I personally think that Standard Imprezza's make a really wonderful exhaust noise, unlike any other I have heard. I was just wondering what it is that makes that throbbing noise - is it to do with the exhaust baffles?

Im not a Scooby driver - I have an MR2 but am curious!!!

its the engine (flat 4)..

the exhaust can accentuate the sound though.. :D

Basically, since the flat 4 has two horizontally opposed banks of cylinders, the exhaust manifold takes gases from each bank separately, and mixes them further back in the exhaust system. However, due to the unequal length of the exhaust headers, when these two exhaust pulses (one from each bank) meets, they are out of phase with one another, and the subsequent throbbing noise is the result.

Hmmm, well it was a lot more complicated than i thought. Do you reckon you could replicate it through baffles in the exhaust? (not going to attempt it - just wondering)

Be easier to buy a scoob!

:D

I guess that as the noise is down to the unequal length headers, that if you developed a similarly unequal length exhaust manifold for straight four you could get something similar. Be a bit odd hacing to have two very long and two short branches in the manifold, and the only reason to do it would be the noise, but could probably be done.