To buy headers or not?

Will 370Z

I’m new to this platform and I am interested in the horsepower per dollar topic. Of course the answer to “is it worth it” and “what should I do” is dependent on the owner’s goals with the car among several other things, but I’m curious about what modifications make the most improvement in power.

From what I’ve read, a good 3” long tube intake system and a tune are a must along with maybe a solid, free-flowing catback and mid pipes, but what would be the best next step? Headers can range from $800-$2,000 plus labor, but some have said horsepower gain is minimal so would it be best to invest in maybe E85 and/or ported intake manifolds etc?

I’m all about horsepower and having a good sounding car, but I also want to give some attention to suspension and handling. Don’t see FI in my future with this car, but I do want to add bolt ons and other things that would make this car even more enjoyable to drive