Never seen anything like an "NP" branding in stock Laverda pistons.
Cast Mondials or forged Assos in the case of the 1000SFC, and perhaps the RGS Corsa. The HC pistons were also available in cast form from Mondial, not sure what the factory fitted to the Corsa as I've not yet had the pleasure of opening one.
Gerald,
Have you found a connection between Asso and Mahle?
piet