I tried to upload the instructions from Hidden Hitch, but msprotege.com won't allow .pdf uploads. They can be downloaded from
www.hitch-web.com , do a search for a 2003 / Mazda / protege. These instructions are great, but there are a few more things to be aware of, esp. with the MSP:
1) The diagonal brace on the back of the Racing Beat muffler has to be cut off or it WILL hit the hitch when the exhaust warms up and lengthens. A dremel works well but use the stock (thin, brittle) cutting discs because this stainless EATS the fiber ones. Ue eye protection. Note that you WILL get dirty. Cut the diagonal bracket BEFORE installing the hitch, you can't get at it well once the hitch is in place (I got to install my hitch TWICE, so I know!). Detaching the rearmost muffler mount helps immensely in doing this, and silicone spray really helps in detaching/reattaching this mount. Mine's been cut for about 400 miles and the tailpipe hasn't drooped or anything, but time will tell - and there's a nice piece of bodywork available right above the tailpipe if another mount needs to be attached/fabbed up later.
2) The bracket for the accumulator will have to be bent a little to clear the bracket on the driver's side of the car. A vise grip and a monkey wrench work well. You'll see what needs to be done when you install.
3) You'll need an 11/16" socket, preferably deep well. You can use a cheap Chinese-built 11/16" like I did, but it's a PITA. The mounting bolt toward the back of the car on the exhaust/passenger side may need to be accessed by open-end wrench.
4) The Hidden Hitch fits very well, I'lll post some "underneath" shots later (my work computer doesn't have those shots on it).
5) The Hidden Hitch is a class 1, meaning there's a tab inside to prevent putting the longer 1 1/4" class 2 drawbars in there. Unfortunately for me, my bike rack was the extended class 2 bar, so I had to dremel this tab out by cutting from underneath and banging it out. Did so, Rustoleum'ed the cut area, and it works GREAT.
6) It's really easy to do this on a lift or on ramps, and our ground clearance is good enough that stock steel ramps were easy to get the car onto.
As always when working under a car and with cutting equipment, PLEASE use proper precautions, wear eye protection (you only get ONE set of eyes), and secure the car by putting the ebrake on, putting the car in gear, and chocking the wheels. There's a lot of grit that gets caught in the bumper/rear valence and it'll fall all over you - be prepared.
Enjoy!