I installed an LED kit in my 2013 Legacy 2.5 Limited. I got the parts from AutoZone. I got the Alpena NanoLEDz for the cupholder, Alpena 24" lightstips for the under dash LEDs and a small switch.
Alpena NanoLEDz
NanoLEDz installed in the cupholder. Then the rubber ring went over top.
Wiring the under dash floor LEDs
Wiring the switch. Got the power from the shifter illumination wires so the lights come on with the car lights w/ the option to turn them off
The final Product
Lights off
under dash lights