I have had it installed for just over a week now and I definitely can tell the improved throttle response. I haven't seen any improved MPG. As for horsepower, I have this installed with the aFe cold air intake and overall I feel more horsepower, but not sure which item really provided the additional horsepower. I purchased because I wanted more power for towing and better MPG. The better MPG is yet to be realized, but I would still recommend to others given the relatively low cost and increased horsepower.