I didn't believe the Hp gain claim, particularly because it was the same gain for every engine displacement. That's not possible. I am an engineer and owned/operated a high performance automotive machine shop for 11 years. The purchase was more out of curiosity to see if the engine efficiency would improve. When I rebuilt the engine, I performed some mild porting (bowl clean-up and short side radius) to compliment the competition valve job. Time will tell if the chip helps either mpg or Hp as claimed. The cost was no big deal for me. Just tinkering. Thanks. I really like the forum and input.