Not sure about the flat sections on the sides of those pistons, the Suzuki factory pistons are a fully round profile ...
I know Rocco Garzone (TripleRocky) had a 400cc GT380 ... the 380s sold in Italy were actually 384cc (55x54mm bore & stroke) as standard, because of a local tax / insurance class, and Suzuki Italy sold 55.5 and 56mm pistons for rebores.
Wonder what difference that extra 7.5% capacity hike makes, with a little light clean-up of the ports?
