[gone-ot]

1) Velocity of sound thru INTAKE system:

Vs(int) = 49.1*SQRT[ T(air)+460° ] - 50

...where: T is air temperature in degrees F; 49.1 is constant for air.

Vs(int) = 49.1*SQRT[ 100°+460° ] - 50 = 1112 ~ 1100 fps.

2) Velocity of sound thru EXHAUST system:

Vs(exh) = 48.0*SQRT[ T(exh)+460° ] - 50

...where: T is mean temperature (exh.valve to tailpipe) in degrees F; 48.0 is constant for exhaust.

Vs(exh) = 48.0*SQRT[ 1010°+460° ] - 50 = 1790 ~ 1800 fps.


P.S.--header pipe is synonymous with exhaust manifold, but is not the same as exhaust pipe, which is what exits (usually) at the back of the vehicle.