[Hectic]

f the are listed like that 150% then they are likely 150% power up from stock.
now u have to figure if they wer alrdy pre upgraded for import with saya 150 or 190% spring or if they all come shooting 400ish. Most airsoft in Japan shoots sub 300 due to their laws and they make stuff "for export only" that shoots higher or stuff made in china is made for Japan or for north american markets at differet fps
to playit safe id get the 150% spring see what it chronos nd then choose wht spring to cut down for yer target fps