The light magnum and high energy loads do not increase the peak pressure. They use a specially designed powder. The powder is soaked in a variation of nitroglycerin, dried and then treated with a coating to inhibit the burning rate. This results in an increase in energy per given volume of case capacity. The powder works by maintaining the pressure longer not by increasing the pressure.
You will find the Hornady Loads in 06 are actually cheaper than the 7mm or 300 WM ammo with equivilent bullets. I shoot the cheap standard 06 ammo at the range and for whitetails and just buy the light mag ammo for elk. It is the best of bothworlds. This powder works best in the 308 and 06 cases. For instance the 165 grain interbond light mags had to have a crimpinggroove added to the bullet because the load was "highly compressed" according to the Hornady tech center.