Okay, yes 120K on GPS is very good indeed (for RX115)
but still, i do not believe 140K on speedo... i think you must re-sync the meter with GPS. Gear, Rim and tyre size also can effecting speedo. Like my friend's RXZ setup (15/40, 17" 2.25 Front 17" 2.50 Rear, factory setup) can reach 160 on speedo, but while testing on straight line, he cannot overtake mine with (17" 80/90 F 18" 100/80 R, custom exhaust system).