How effective are cam gears on the jdm 16v 4AGE?

I ask this as i am new to the world of 86's, and only really have experience with skylines etc.

Do they just compliment camshaft modifications/ upgrades?
Or can they be used as a modification on their own?
What are typical power and torque gains?
Are they largely in the mid range, or do they add more top end whack?

Cheers,
Mick