Feeling the results of a fix makes inconsequential every penny paid for it . I first worked on cars nearly 60 years ago and, since then, worked on race teams with motorsports' best wrenches using the most advance technology. About the Griffin guys, I can't say too much. My 20-year-old A4 runs like when first upgraded with Abt bits and pieces, pulling and pulling and pulling until there's no RPM left.