yes it is true, my dad bought a 9.9 johnson in 87 and had it, what he called boarded out the carb. to a 15 i wish i could tell you more but i don't know much about it just know you can do it. my pop's is up fish'n the big pond in the sky so i can't asked him but we were the fastest 9.9 on the lakes sure someone will have more info, good luck!