i am a newbie!, and have no idea wat to do to get more power out of 5 gear? at like 110mph(4200) it seemed like its struggling to make RPMs so i put a 4:1 header on it hoping it would help horsepower but it seems to lag at 115mph(4600) now. im not sure wat to do. i have a cai, dc sport 4:1 header, high flow cat, Invidia cat back exhaust system. wat else is there that can add power in that RPM range?