I wouldn't hesitate to get a kleeman system. Just make sure the place doing it is Kleeman certified. The actual kleeman co. in Colorado Springs will dyno your car before and after (at least they do with MBs). There are tons of MBs that go with kleeman and even ship their cars out to CO springs directly so Corey can work on it. I don't know what kind of power it will give the Crossfire but I know of some E55s putting out over 550 hp with their K cars. Hope this helps. I'm a mercedes die hard and I am hoping to get a E55 in a year. I bought my wife the crossfire in hopes that it will justify my car.