Your metamagic spells function as higher level spells.
Prerequisites: Heighten Spell.
Benefit: When you add a metamagic feat to a spell, its effective spell level actually increases.
Example: A sorcerer with this feat that casts a silent still fireball as a 5th level spell calculates its save DC as a 5th level spell, and can affect targets within a lesser globe of invulnerability.
Normal: Normally a spell with a metamagic feat (other than Heighten Spell) does not count as a higher-level spell for such things as save DC and the ability to penetrate a lesser globe of invulnerability.