Heighten and Spell Penetration items

[TheWalruss]

Hey

I was wondering if I heighten a lvl 6 spell to a level 9 spell, how does spell penetration items affect that spell? Will spell penetration VI be applied to my heightened spell or do spell penetration IX items now only affect it?

Mordiggian of Cannith

[Rodomonte]

It's still a sixth level spell for item purposes (Spell Pen, Potency, etc).