5500 feet means your engine can't get as much oxygen, so it can't burn as much fuel, and it won't produce as much power. I used to be an Air Force flight engineer, and we had tables and charts to calculate how much power an engine would make at takeoff according to altitude and air temperature. Even with the turbo helping, an engine is going to be a lot weaker at that altitude.
Mine is a stick, so I rev to about 2500 rpm, pop the clutch as I floor the gas, and use the Cobb's flatfoot shift feature as I go into second gear about 5000 rpm.
Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere. - Colin Chapman