Do a search on the forum and the net. The 2.4, also used in the Neon and PT Cruisers is a dual overhead cam, 4 valve engine and from what I have read, responds well to cold air intakes and exhaust mods, unlike the 2.5s and 4.0s that most of us have. Our next door neighbor has an 03 with the 2.4 and he rigged a home made cold air intake and said it has made a noticeable difference in performance and gas mileage. He is running 31s with 4.10 gears and a 5 speed. The po had replaced the stock muffler with a glass pack. Too loud for me but it is not obnoxious. He's 18 so he loves it. I haven't researched it but I bet you could get mild performance cams that would help too, but don't know if computer can keep up with them.