I'm thinking that it will tweak both opening and closing of the throttle. When I had my 'Stang tuned, Eric tweaked the drive-by-wire settings and it not only helped acceleration, it allowed the car to back down immediately when getting off the gas. Whether the DS canned settings will be that sensitive, I don't know. I might play with it tomorrow and see what happens. After driving the car for several days now, I'm liking the canned tune a little more. The car accelerates smoother and power is there throughout the curve. I haven't experienced any knocking as some other folks have, but I've been running premium (93-octane) since day one. I also haven't been fooling around with trying to change what DS put into their tune; I haven't changed spark advance, A/F or anything like that. So, the canned tune is working well for me. I'll leave the wizardry up to Eric.