I just got back from my first ride after installing my sprint booster - First off my kick-down works fine. I gotta tell you I don't know what makes that thing tick but it's kick-***. Before I installed this I use to feel as if I had a four banger. I know just reset the computer but after a few hundred miles it was back to the same old slow take-off. After installing this, it feels like a V-8 at low speeds and take-off. This is the best $280.00 I've spent on my car. I'll write back after a few hundred miles to let you know if it gets sluggish. I'm thinking it won't because I did not reset the computer after the install.