To get the speedometer reading correctly and help up the power levels on the ’04 Tahoe, we installed a Superchips Flashpaq. The Flashpaq is great for modified and stock vehicles because it allows you to alter the tire and gear ratio calibrations and choose from a host of performance and fuel economy programming tunes, and it also works as a diagnostics tool. In this modern age of computerized vehicles, a handheld tuner is like having a toolbox that fits inside your glovebox.