I like the OBD 1 D16Z6, only because my last engine was the D15B7. The Z6's are the most upgradeable. If you want to get more out of your D16 the best head to use is the Y8 head, had pentroof-style combustion chambers with generous quench zones. This head will raise your compression ratio by a half point. The pistons from a 86-89 Integra motor (D16A1 I Believe)bumps the compression about 3/4ths of a point. If you have a vtec D motor...with these pistons and the Y8 head, this will get you a high 10:1 ratio.......Just something I thought of doing to my Z6, Well I prepare for a B-Series.