I didn't notice a big performance gain. I had mine pretty dialed in though before the fitech went on. I wanted it running perfectly with the carb so that I had a good baseline to troubleshoot any issues. My ignition system, fuel tank, fuel lines, intake, exhaust (manifold back) is all new. I have had it shut off on me a couple times and not want to start back for a few minutes but I "think" I have traced it down to a bad connector where the fitech battery wire goes to a fuse block I have on the inner fender. It pulled apart on me when I tugged on it so I'm hoping that was the issue. I drive mine most days when it doesn't rain (have to replace windshield gasket).