A PD blower like KB / M90 etc makes big low n mid range torque vs a Pro Charger which to me is more important / fun vs peak h/p.
Gains with headers on a milder set up are minimal, good mid pipe n cat back is really all you need unless targeting a max effort.
On mild set up n safe tune, expect to make 400/400 at the tires, yes it's capable of more if you desire.
While that may seem tame compared to some, keep in mind it'll start making appreciable power n torque in the 2000rpm range.