Most of my difficulties were due to the lack of instructions. I also did not yet have my Mazda workshop manual or the Enthusiast Manual, so at first I really did not know what to do.
Any responsibility in trying this is yours. The car may fall on top of you and kill you, for example. The sway bar might come off during driving. Read and understand all information before you start. This includes the instructions below, the instructions that came with your jack, chocks, and stands, and your car's instruction booklet on the dangers of jacking.
Needed (at least, this is what I used): sway bars; urethane bushings (later replaced by Delrin bushings); hydraulic jack (maximum height collapsed 5 inch, from Sears), stands and chocks to jack up the car; 10, 12 and 14 mm sockets; 14 mm deep sockets; socket wrench; torsion wrench (needs to go to 33 ft lbf); 14 mm box wrench; anti-seize compound; measuring tape; teflon tape (plumbing section); typist correction fluid. Six point sockets might be better to get the very tight 14 mm nuts off.
The bolts are tight. Use some liquid wrench or WD-40 on them a day before you start working.
I found it very difficult to get the bars exactly symmetric. I suggest that before installing the new bars, you mark off the *exact* center of them using the typist correction fluid.
Car on a level surface, and especially left-right level. Gear in reverse and the brake on tight. Chocks behind the rear wheels. For the front bar, the jack point is at the center of the horse-shoe-shaped cross member between the front wheels. Make sure some of the jack head is pushing at the bend edge of the beam, which is stiffer than the exact center point. I did not, and mine deformed a bit at the center. I left the car supported by the hydraulic jack in addition to the stands to be more safe, maybe. Don't hit your head on it, though. And make sure the stands *are* supporting the car. Use the 10 mm socket to take off the plastic protective bottom below the engine. Note that there are two different kinds of 10 mm bolts. Cover the insides of your new urethane bushings with anti-seize compound. I had been told a thin layer, but mine started to make noises, and I had to go back and put on more. So I suggest you apply it liberally. Now put your bushings on your new sway bar and put them at the exact same position as they are on the stock sway bar. Wash the anti-seize compound from your hands before touching anything else.
Below the car, take off the nuts holding the brackets with the rubber bushings in it. Now take off the bolts holding the ends of the bar to the links.
Install the new bar in inverse order, but only loosely tighten the bolts. Don't get any anti-seize compound on the bolts or nuts; I had a rear one come loose. The new brackets come with rings to put below the nuts, but because of the curvature of the brackets, I could only get one on each bracket at the front, and none at the rear. I did a slight bit of bending of the brackets to improve the fit. Check for symmetry. You need to put the car down on its wheels before you can tighten the bolts. I put double issues of "Computer Shopper" below the wheels before putting them down to have *some* space to work left. Wood plates are probably safer. After the car is resting on its wheels, tighten the bracket bolts to 17 ft lbf and the end bolts to 33. I could not get the torsion wrench to work on the end bolts, so I just made them tight.
For the rear, the jack point is at the center of the differential; again, make sure that the head of the jack is well supported before lifting the car. Make sure you use the innermost holes on the rear sway bar. If you use the outermost, as I did at first, the heads of the bolts will get in between your springs. For the rest, the rear bar installs the same way as the front one. The torques are also the same.
I suggest that you keep an eye on the tightness of these bolts. I had one rear end bolt coming loose twice before I cleaned the anti-seize compound off it.
Since the urethane bushings kept making noises, even with the anti-seize component, I ordered myself a set of Delrin bushings. Miata Magazine suggests to wind a single layer of teflon tape around the bar, since Delrin bushings can make lots of noise if they get wet. I put a small piece of sticky tape at the end of the teflon tape to make winding it easier.
The Delrin bushings must be installed with the original Mazda brackets. You need to file a small protusion away to do so. Unfortunately, I had already thrown away my old sway bars along with the brackets. Fortunately, Joe at Brain-Storm still had an old pair of brackets lying around, already filed, and send them to me for free! How is that for service?
The steering effort has slightly increased, which I actually prefer over stock. (I have power steering, but it does not do much at speed.) I still need to have my alignment changed to the recommendations of miata.net, which I understand compensates for the heavier sways. The car will still drive straight long distances without me holding the steering wheel. It is one of the upgrades I like most.
As noted above, the urethane bushings kept making noises, even with the anti-seize compound recommended by Miata Magazine. The anti-seize did reduce the noise and limit it to deep areas in the road (i.e. to large wheel travel.) But the Delrin bushings do not make noise at all. If you upgrade your sway bars, I recommend that you order Delrin bushings with them.