When I first got my '04 SE S/C it seemed like it had a parachute behind it. I bought it several states away and drove it home through the mountains. The more I drove the less oomph it seemed to have. Read some posts here and more on another X site and heard about an easy thing to try that worked wonders for me. Disconnect the battery for a minute and turn on the headlight switch. I dont know if the headlight thing really discharges ECU memory capacitors or not but it was in the post I read. Any way... Made a noticeable difference in my case. Makes the computer re-learn fuel/air ratios and timing curves. I think it helped after moving it to a higher elevation and using local mix gasoline. Every state, and even some counties have regulations on retail fuel additives. Give it a try! Nothin' to buy!