cam question

Is it worth putting a cam in a D16y7 how much horsepower and torque do you think i will gain if i add this. Can anyone tell me what you all need to install the cam and shaft. Plus someone told me that if i put the cam in i would need to have the timing ajusted or the pistons will be pushed through the engine block. I don't know anything about this so tell me as much as you can. thank you