2.3 Improvements
 

Ive heard from various people that putting a Ranger Exhaust manifold, roughly close to the same year as your mustang will improve a little horsepower.
Has anyone heard of a company that makes cold-air intakes for 4cyl Mustangs?

I don't know about a company that makes a Cold Air Intake, but for a few bucks and a little enginuity, Home Depot has a lot to offer. Good luck