just placing the exhaust tip willy nilly somewhere may put it in an area of pressure or ...
so
it would not be too hard
to measure , just get a MAP or FuelTankPressuresensor sensor from somewhere (junk yard) get the connector too ...
three pins on the MAP or FuelTankPressure sensor.
power 5v , ground , signal .
,tap into the 5volt reference in the car OR make up a 5v power supply , use a dvom or labscope on the MAP or FuelTankPressure sensor sensor signal pin
and position a vacuum line from the MAP or FuelTankPressure sensor in the car
to the area you suspect has lower "pressure " , drive the car .
not moving signal voltage will be about 4.5 volts on a MAP sensor from GM or 3 volts on a Honda MAP sensor , what ever the value
assign it to be "local Ambient Barometric pressure "
for this test ;
lower voltage is better because it will show (lower pressure),
you will be searching for the vacuum hose position that yields the lowest value
there are charts that will give up voltage vs "pressure" values.
depending on which MAP or FuelTankPressuresensor you can scavenge from ...
a FuelTankPressure sensor will have better resolution .(differences will be easier to measure and see)
or use a real pressure transducer .
or a water filled vertical "U" shaped tube with the vacuum line on one end of the "U" permanent marker graduation s ...
either way , differences will not be large
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