I believe the astra disc doesnt need the spacer ring. Thats for using levin discs, it goes under the disc between it and the hub to center it in the caliper. 260s fit fine, you can fit 275mm discs with levin calipers under 15s fine, stock starlet are 256mm anyway. And yes in somecases you do need you clear the arch between carrier bolt holes others you dont. If you want to make the kit 275mm just use celica st202 carriers and only get the astra disc skimmed to 275mm.