t2 housings n/a internals

[GtoRx7]

Originally Posted by Low Impedance

on the other hand, auto manufacturers aren't looking at just power output.

Once you start porting engines, playing with tuning etc, the fuel economy, drive-ibility, reliability, etc change. Emissions comes into play. The switch from the 4 port 13b to the 6 port 13b was probably just a function of the above. Plus Mazda seems to enjoy experimenting with new ideas.

Couldnt say it better myself. Performance vs. Stock, and the changes needed between the two are so different. Torque between 1000-3000rpms is SO important to mazda in a factory car. If my engine had to have full cats, air pump, etc it would have less torque in this area without a doubt.