Lowering springs for 3rd gen

[m.flores.0928]

What lowering springs do you guys recommend for a third gen yaris?

Also, I found that you can get springs from TRD for Scion xD, are they also compatible with third gen yaris? I wonder if they are because the rear sway bar is compatible, among many other parts.

Also also, I would like progressive spring rates for the rear, something like how the more you compress it, the stiffer they get, because with my wheel situation in the rear, the tires rub on the top of the rear fender when there is weight in the back (passengers, etc) so I figure with progressive spring rates, I can minimize rub even if it's lowered by limiting suspension travel.

To that end, should I look at rolling my rear fenders too? I hear that's something I can do to minimize rub also.

Thanks guys!