In this particular case...no. The 340 was underrated for various reasons. It was actually around 315hp.
There's a few reasons why net hp was mandated... not voluntarily adopted. Net ratings are real world. An engine is pulled from the line and randomly tested, and independently verified. It is also configured for the application (air box, exhaust, ect for the car to be installed in). This is why an identical engine may be rated differently when installed in different vehicles.
