I had a similar Metamagic system and the forum here tore me a new one. They basically showed that this kind of system breaks down at high levels. But in case you don't beleive that or can figure a way to tweak it so it can't be unbalancing at high levels here it is.
EMPOWER SPELL [METAMAGIC]
Benefit: All variable, numeric effects of an empowered spell are increased by one-half.
Saving throws and opposed rolls are not affected, nor are spells without random variables. An empowered spell uses up a 2nd level spell slot in addition to its normal spell slot.
ENLARGE SPELL [METAMAGIC]
Benefit: You can alter a spell with a range of close, medium, or long to increase its range by 100%. An enlarged spell with a range of close now has a range of 50 ft. + 5 ft./level, while medium-range spells have a range of 200 ft. + 20 ft./level and long-range spells have a range of 800 ft. + 80 ft./level. An enlarged spell uses up a 1st level spell slot in addition to its normal spell slot.
Spells whose ranges are not defined by distance, as well as spells whose ranges are not close, medium, or long, do not have increased ranges.
EXTEND SPELL [METAMAGIC]
Benefit: An extended spell lasts twice as long as normal. A spell with a duration of concentration, instantaneous, or permanent is not affected by this feat. An extended spell uses up a 1st level spell slot in addition to its normal spell slot.
MAXIMIZE SPELL [METAMAGIC]
Benefit: All variable, numeric effects of a spell modified by this feat are maximized. Saving throws and opposed rolls are not affected, nor are spells without random variables. A maximized spell uses up a 3rd level spell slot in addition to its normal spell slot.
An empowered, maximized spell gains the separate benefits of each feat: the maximum result plus one-half the normally rolled result.
QUICKEN SPELL [METAMAGIC]
Benefit: Casting a quickened spell is a free action. You can perform another action, even casting another spell, in the same round as you cast a quickened spell. You may cast only one quickened spell per round. A spell whose casting time is more than 1 full round action cannot be quickened. A quickened spell uses up a 4th level spell slot in addition to its normal spell slot. Casting a quickened spell doesn’t provoke an attack of opportunity.
Special: This feat can’t be applied to any spell cast spontaneously (including sorcerer spells, bard spells, and cleric or druid spells cast spontaneously), since applying a metamagic feat to a spontaneously cast spell automatically increases the casting time to a full-round action.
SILENT SPELL [METAMAGIC]
Benefit: A silent spell can be cast with no verbal components. Spells without verbal components are not affected. A silent spell uses up a 1st level spell slot in addition to its normal spell slot.
Special: Bard spells cannot be enhanced by this metamagic feat.
STILL SPELL [METAMAGIC]
Benefit: A stilled spell can be cast with no somatic components.
Spells without somatic components are not affected. A stilled spell uses up a 1st level spell slot in addition to its normal spell slot.
WIDEN SPELL [METAMAGIC]
Benefit: You can alter a burst, emanation, line, or spread shaped spell to increase its area. Any numeric measurements of the spell’s area increase by 100%.A widened spell uses up a 3rd level spell slot in addition to its normal spell slot.
Spells that do not have an area of one of these four sorts are not affected by this feat.
Maybe increase the spell level to use the Feats?
EMPOWER SPELL [METAMAGIC]
Benefit: All variable, numeric effects of an empowered spell are increased by one-half.
Saving throws and opposed rolls are not affected, nor are spells without random variables. An empowered spell uses up a 2nd level spell slot in addition to its normal spell slot.
ENLARGE SPELL [METAMAGIC]
Benefit: You can alter a spell with a range of close, medium, or long to increase its range by 100%. An enlarged spell with a range of close now has a range of 50 ft. + 5 ft./level, while medium-range spells have a range of 200 ft. + 20 ft./level and long-range spells have a range of 800 ft. + 80 ft./level. An enlarged spell uses up a 1st level spell slot in addition to its normal spell slot.
Spells whose ranges are not defined by distance, as well as spells whose ranges are not close, medium, or long, do not have increased ranges.
EXTEND SPELL [METAMAGIC]
Benefit: An extended spell lasts twice as long as normal. A spell with a duration of concentration, instantaneous, or permanent is not affected by this feat. An extended spell uses up a 1st level spell slot in addition to its normal spell slot.
MAXIMIZE SPELL [METAMAGIC]
Benefit: All variable, numeric effects of a spell modified by this feat are maximized. Saving throws and opposed rolls are not affected, nor are spells without random variables. A maximized spell uses up a 3rd level spell slot in addition to its normal spell slot.
An empowered, maximized spell gains the separate benefits of each feat: the maximum result plus one-half the normally rolled result.
QUICKEN SPELL [METAMAGIC]
Benefit: Casting a quickened spell is a free action. You can perform another action, even casting another spell, in the same round as you cast a quickened spell. You may cast only one quickened spell per round. A spell whose casting time is more than 1 full round action cannot be quickened. A quickened spell uses up a 4th level spell slot in addition to its normal spell slot. Casting a quickened spell doesn’t provoke an attack of opportunity.
Special: This feat can’t be applied to any spell cast spontaneously (including sorcerer spells, bard spells, and cleric or druid spells cast spontaneously), since applying a metamagic feat to a spontaneously cast spell automatically increases the casting time to a full-round action.
SILENT SPELL [METAMAGIC]
Benefit: A silent spell can be cast with no verbal components. Spells without verbal components are not affected. A silent spell uses up a 1st level spell slot in addition to its normal spell slot.
Special: Bard spells cannot be enhanced by this metamagic feat.
STILL SPELL [METAMAGIC]
Benefit: A stilled spell can be cast with no somatic components.
Spells without somatic components are not affected. A stilled spell uses up a 1st level spell slot in addition to its normal spell slot.
WIDEN SPELL [METAMAGIC]
Benefit: You can alter a burst, emanation, line, or spread shaped spell to increase its area. Any numeric measurements of the spell’s area increase by 100%.A widened spell uses up a 3rd level spell slot in addition to its normal spell slot.
Spells that do not have an area of one of these four sorts are not affected by this feat.
Maybe increase the spell level to use the Feats?
