Just bought a 2011 Legacy 2.5 premium and want to get the best computer chip to increase my MPG and horse power.  Anybody put one in their Legacy or other model and have good results.  Looking for any recommendations.

No such thing exists, and if it does, it's a hoax. Just enjoy your car.

Ditto, pure snake oil for suckers. You can load a different tune onto the ECU but for a naturally aspirated car the gains are not really there without radical modifications.