I've read that it roughly adds 6 horsepower to the xB. Does it increase fuel efficiency as well?

 

Fuel efficiency depends on the weight of your foot! Higher performance capability tends to lead to worse gas mileage, not better, but that's typically due to the driver, not the technology.

 

youre not going to gain mpg if thats what youre asking. i lost about 1mpg with my AEM CAI but as TrevorS points out i have driven slightly more aggressively on the street and that may account for my average drop of about 1mpg

 

My sentiments exactly. I actually laughed when I read the last part though

 

i have one for sale if your interested