* 2.3L 4-cylinder: Around 90-100 horsepower.
* 5.0L V8: This is where it gets more variable. Early in the model year, it was around 225 horsepower. Later in the year (and depending on the specific trim), it could be closer to 220 hp due to changes in the catalytic converter.
To find the exact horsepower for a specific 1989 Mustang, you need to check the vehicle's documentation (like the owner's manual or the vehicle identification number (VIN) sticker).