t2 housings n/a internals

[vex]

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.

That's true, but a street port shouldn't adversly affect those to the point of failure. The regular NA has 3 cats to pass US emission standards. The only difference I can actually see with regards to the engine is the 6pi and their only function is to increase low end torque. I'd like to see a dyno chart of a 4port na compared to a 6 port na and look specifically at their torque curve (below the 3500 rpm mark).