Give him 10 out of 10 for experimenting.
I played with a similar Idea years ago ,trying to bring down the decibels on a racecar without using restrictive mufflers.
The idea is to "pipe off" some of the gas-flow and re-route it via a longer and narrower path [ to increase gas velocity ]
Then when it re-enters the normal gas flow the two different velocities change the frequency by smoothing out pulses [and cancelling out sound-waves].
It worked OK[ish] , but an exhaust gas equalizer worked better [ 2 "U" bends welded together as a crossover pipe ]