Best Cold Air Kit for '90 LX 5.0?

The best cold air mod for a Fox Mustang is to remove the silencer and leave the rest of it alone. Maybe add a Green filter or a foam filter.

A cold air kit can NOT improve the performance of a near stock Mustang (one without performance heads). It WILL most lilely hurt performance and driveability.

The stock MAF (and most aftermarket MAFs) require a linear column of air to measure correctly. The stock air box and filter provide this. Cold air kits, or anything else that puts a sharp bend in front of the MAF screws up the linearity of the airflow. The MAF will read too little of too much air and you'll end up with the wrong A/F ratio, hesitation, or worse.

You can "clock" the MAF to compensate for this or better yet use a MAF that samples from 360 degrees. But why got through the expense a trouble for nothing.

Full disclosure: I use a cold air kit on my 430 hp 331 stroker. I also use a Pro-M Univer MAF.

LJH