Complex sentence: The SX is only available with the 3.5L 276hp V6, while both the EX and LX comes standard with the 175hp 2.4L I4 with V6 as an upgrade.
Split into simpler sentences: The SX is only available with the 3.5L 276hp V6. Both the EX and the LX comes standard with the 175hp 2.4L I4 with the V6 is available as an upgrade.