i have a d15z1 is it possible to put a new head and change out the intake manny? if so what head would be best?

 

Leave it alone or swap the whole thing.

 

^ +1. The combustion chamber of the D15Z1 head is much smaller than most (if not all) other D-series heads. With any other head on there, the compression ratio is going to be super low; too low to effectively make power.