In my personal experience, I never really got what was promised out of various plug-in performance or efficiency enhancements.
What does work are custom "tunes" a performance shop will tailor and test specifically to your vehicle. Another option is what I tinkered with:
(Not a sponsor, not a plug)
Diablo Sport sells a box, cable kit and depending how deep you want to get, a software app you run on your laptop. It saves an original memory flash from your on board computer, then loads in a broad spectrum enhancement that does work. You can tell it if you have certain mods, built on parts, etc. and it will dial your vehicle into optimal shape.
You can choose blistering, boosted intake, chopped exhaust and NOS matched tunes, or massage a stock rig into enhanced performance or super economic modes. You can always flash back in original saved parameters and fuel maps if you remove mods or need to roll your machine in for service.
If you go with the laptop app, you can actually dig into the digits, shift points, shift pressures, speedometer calibration... all of it. But! Be very aware and know what you're doing. If you don't, or have something completely out of the box in mind, you can email Diablo Sport with your request, specs, what you expect...then they'll send you a custom tune you then flash in.
It may take a few tries of saving snap shots, emailing them, receiving... wash, rinse, repeat; but they'll set you up. (As long as your subscription is paid)
But here's another clue... it's costlier by orders of magnitude than any $40 clip and forget gizmo. You get, rather unfortunately; what you pay for in this arena.