I have the MRZ UDP. No problems with install or use. I didn't do a before and after test to know what it can really do. I like the fact that it slows the Alternator and AC compressor by about 10% (2.4 auto has 3.91 gear Vs 2.2 auto 3.63 gear so the UDP slows the Alt and AC Comp to 2.2 speeds on the highway -- this was something GM did in the 60s when you bought a car with high numerical gears.) Too bad we cant slow the waterpump too -- that would be a graeater gain.