I thought I read it was actually more restrictive.
Not sure but here's the quote from the article;
"It's one that Chevy fans have forgotten about because it doesn't have one of the 396 mill", (referring to the L48) the Hoosier State owner explained. The point must be made that this particular 350 engine makes more than the factory figure, and it's done with a factory available option. "The car carries an optional chambered exhaust system which provides for a more free-flowing exhaust and a slight increase in horsepower, probably pushing it very close to the 325-horse 396 engine."
Sure hope we can get it confirmed one way or the other here...