Have an 08 EGC. Installed Xieds a couple of mos ago. Definate improvement on the throttle response. I can't say it cooled the engine off to a noticeable degree but I like having them b/c it is comforting knowing the ratio is a little richer with fuel regardless. If you plan on doing any engine mods, I would go with a management system as Xieds are not adjustable. Do a search on this topic, you will find many opinions. Smitty is even conducting an ongoing test of his. The MPG drop can be drastic if you twist the wick too much. When first installed mine went from around 40 in the city down to 31 MPG. However, my highway miles kept at 65 -70 my MPG was 39.8, which is a drop from the previous 45. Just pay attention to your throttle and it ain't too bad.