I have a '91 std hb (d15b2). I want to know whether I should install a d16z6 head with the d15b2 bottom or just swap a complete d16z6. Can someone explain to me what differences in performance I can expect by doing either one? Thanks.

 

since you live in ca you shouldj ust swap in a d16z6 because using a different head not originally made for your motor is illegal. you'll aslo be making more power and torque with the d16z6 anyways due to more displacement.