I'm in the process of deciding if I shold go for a '96/'97 Miata (less expensive/OBE II) or the '99 Miata (more potential/ more expensive). Specifically, there is the issue of the '99 head over the '96/'97 head. Is there something in the '99 head over and above the 7 bhp factory increase beyond the '96 to '97 to strongly justify its installation on earlier 1.8's? Incidentally, I'm only planning some intake, exhaust, and valvetrain mods on a built longblock.

 

99 head flows better. 99 engine has higher compression pistons. 99's also have vics.

When I was shopping for mine, I test drove a 92, 94, 96, and finally a 99.

The 92 with the 1.6l was the first miata I had ever driven and I loved it. Very rev happy little motor, but it had 170k on it and the crank pulley was wobbling so I didn't get it. The 94 was also nice, a little more power and seemed to handle slightly better but it smelled of antifreeze and I think the head gasket was going so I didn't get it. The 96 I almost bought, very clean low mileage car (68k) but the guy wanted $4500 and it needed tires and brakes immediately and the a/c didn't work so I didn't get it.

When I went to see the 99 I didn't like it. The tan top was ripped, the driver seat was cracking and the bumper had some paint flaking off. But it had a hardtop and the leather package and the torsen and the 15" wheels, etc.

After taking it for a quick test drive on the freeway it was apparent that the motor was much stronger than the 1.6l and even the 96 felt weaker in comparison. Could be the gearing?

Anyway, I am glad I picked the 99 and even more happy now that it's boosted. Seriously, you should turbo it. For the money you'll spend on I/H/E and headwork, you can bolt on 60-80hp with a cheap turbo kit.

 

the '99 has straighter ports on the intake, solid lifters, slightly more agressive cams and requires a 99+ intake manifold. In naturally aspirated form its worth 10-15 hp over the 94-97 head.

If I was going turbo, I would not bother with the 99 head unless I had one already.