I figured I'd chime in since I installed mine 2 days ago. I have to say it absolutely transformed the car for me (6MT here).
Everything is stock so far, but it truly changed my experience with the car and the manual transmission specifically. I had been thinking about buying a short shifter, bushings, etc., to improve the 6MT (as we all know leaves a lot to be desired), but with the pedal tuner I am debating whether I truly need it. To elaborate more, this is my 1st manual car so I have been trying to get better at quickly shifting gears to get the car up to speed. Unfortunately I always struggled to quickly shift and not feeling like I was sloppy with the shift. The pedal tuner allows me to entirely eliminate that and get the car going fast between shifts. That's the best way I can describe it. It does feel like the oem pedal is a huge factor on the issues I was having.
I've only tested it in the 1st and 2nd setting, but it's absolutely great. Like it was said above me, I almost feel like I don't need to tune the car because it just feels faster with it.
Not to ramble on, but I feel like I need to say this (I will try to explain it to the best of my ability)... It feels like it removes the lugging of the engine feel at low rpms and during shifts. It also feels like I can more consistently keep Rpms steady when in 1st and 2nd gear, removing a lot of the bucking due to the high torque.
No noticeable difference in MPGs yet, but I can report back. Installation is 5 minutes or less honestly.