found this neat info in our facebook group whereas a fellow filipino based on thailand made various test fits on what spring / shock combo will fit and be stiffer than stock.
they used rear springs from a 2006 Honda Fit / Jazz.
optional is rear shocks from a 2007 Yaris / Vios. but this made the ride super stiff. the springs would do just fine.
though the ride height would increase about 1" on the rears