Looking into getting better MPG and ran across rs4 performance chips. 2 of them: $69.99 improves HP +50 Torgue +50 MPG 3-7, $89.99 gas saver chip improves HP 40+ Torque 40+ MPG 7-10 MPG. They also are suppose to improve shifting and a whole bunch of other things. Supposedly 10 minute install.
Any thoughts? Do these work? working on 1999 Sport 4.0L 6 cyl. manual tranny.