that is called a "hunting tooth" setup - and I used it on OS.61 setups (factory) in the early 1980's.
On a tuned pipe -with the "2.91-1 " whatever it was -and a big dose of nitro -this setup really smoked --the noise tho was simply awful .
We flew -at the time - big scale pattern ships which really worked but the "pattern" crowd , simply hated it.
It looked scale and sounded like an air raid siren with a wild undulating pitch.