[oldskool]

The deal with the factory parts upgrade is explained in more detail in this part of an Arnie Beswick bio article.

"... the 1960 Ventura was his first "specialty built"
Pontiac. It was factory rated at 348 HP, however optionally included in the package was
a set of heads and camshaft that raised the horsepower to 363. These parts were covertly
shipped in the trunk of the car. It also came with what is believed to be the first factory
installed 4 speed transmission in a Pontiac. Arnie, shortly after getting the car, drove to
Daytona Beach, Florida for the NHRA/NASCAR Winternationals. The best in the land
were here, so competition would be fierce. The window sticker was purposely left on the
car to prove that it was not modified. The car was still protested, even by other prominent
Pontiac racers. Additional build sheet confirmation had to be sent from Pontiac before he
could receive the overall S/S award for the weeklong competition.

By 1961, he was racing a new Pontiac that was absolutely unbeatable. He started out the
year by traveling to Daytona Beach for the weeklong competition for the second time.
He again won his class as well as going on to win the overall S/S eliminator title. In what
was later another high point of the year, he successfully raced one of the most highly
publicized Pontiac teams in the country. This was the Royal Pontiac crew from the
famous factory supported dealer in Royal Oak, Michigan. It was a best of five match race.
In spite of being an independent with no sponsorship, Arnie defeated the highly favored
Royal team three straight times. He ended up the season going to Indianapolis for the
NHRA nationals. He won in the S/S class, beating out everyone including Mickey
Thompson, who was driving his personal SD421 Catalina. He complied too quickly to the
automatic teardown of all class winners, and was disqualified for being a mere thousandth
overbore on one cylinder as the engine hadn't cooled sufficiently yet..."