Heat is the enemy of horsepower. One simple way to keep heat from slowing your Honda Civic down is to use a thermal intake manifold gasket to prevent the heat in the cylinder head from transferring to the intake manifold. Skunk2 thermal gaskets are designed to bolt on like a stock gasket and prevent that heat transfer. When the intake manifold gets hot, it heats ups the intake charge on it's way to the motor, making the air less dense. Less dense air means less oxygen, which means less fuel can be burned, and less power made.