I would like to know what is better for performance and mpg on a stock 87 5.0. Either Speed density or Mass Air Flow?

 

if its stock, it really doesnt matter. but when you start adding things like TB, intake, cam, heads, cubic inches... the factory SD system will become a hindrance.

 

The question was if it was regarding STOCK performance. To quote "The Official Ford Mustang 5.0 Technical Reference & Performance Handbook":

"An OE or mildly modified 5-liter H.O. motor equipped with a speed density system will outperform a mass-airflow system (on a comparable motor) in wide-open-throttle operation. This is due to the speed density system's slightly leaner calibration and the lack of a restrictive mass-air-flow meter in its inlet tract."

 

See scanned page from book.

 

This is the response I was looking for thank you. Hard to find this information only thing people talk about is if its better for modified engines.