Just came back from a "show". Vendor was Guaranteeing 15% mpg gains", 80+ RWHP for our Cummins, all with a 90 day refund if not satisified! The plug-in safely works the "Combustion Efficiency Process", rather than "over fuel and re-program" our engines. The add also states no mods to intake or exhaust are needed? Anyone using this device? It's a product of Dr. Performance. They also say the device is not detectable by vehicle ECU. Anyone using this? thanks, Doc