Elves as sorcerer +2 spell penetration racail stack with others?

So I always see recommendations of asamir for sorcerer.

But Elves have a +2 spell penetration.
So if this stack with Sylvan sorcerer at lvl 15 and with spell penetration and greater spell penetration feats that will be +8 levels for enemies to overcome, sure I lose one spell use per/day but +2 penetrations seems better especially on harder difficulty but question is do they all stack ?