Performance enhancing chips. Good or bad?
I was browsing e-bay and found this performance enhancing chip for my Xterra that promises to enhance horsepower and improve gas mileage up to 40 MPG. Does anyone have any experience with these things? Is this really possible? Is it a scam? Will it mess up my car? Should I do it or just move on?
This question is in the General Section. Responses must be helpful and on-topic.