This is the expensive way for Direct Fire Ignition:

The ignition system on a rotary, or any other engine for that matter, cannot be ignored when performing horsepower mods. If you are still using a distributor, you are losing horsepower. Period! If you have a second or third generation RX-7, you already have an excellent ignition system. These systems are direct fire, with a "wasted spark" setup on the leading Ignition. Direct fire ignition systems deliver a hotter spark, and the timing is much more stable. As an added benefit, you don't have to change your cap and rotor every other week to keep you car running well.
These direct fire systems are very good, but still leave room for improvement. The biggest problem is that the bean counters at Mazda, and all other auto manufacturers have more to do with the finished product than the engineers do. In other words, make it as cheap as possible. These distributorless systems are known as an inductive discharge ignition. Inductive discharge ignitions suffer from poor spark at high rpm, and this is aggravated by the wasted spark arrangement on the leading ignition which fires twice per revolution. Without going into a lot of detail, the simplest explanation is that the coils do not have enough time to build a strong magnetic field at high rpm, and so the spark continues to weaken as the engine speed increases. The bean counters don't give a shit, because this system works great at low speed, and gives good mileage and driveability. This is the number one priority, even in a sports car.

Buy an MSD 6A

Luckily, this is easy to fix. Buy an MSD. In case you didn't hear me the first time, Buy an MSD! Every vehicle on the planet should have one, even your grandmothers grocery getter. The MSD is a capacitive discharge system, which does not loose spark intensity at high rpm. Capacitive discharge systems deliver a very strong, but short duration spark. To overcome this, the MSD delivers multiple sparks over twenty degrees of eccentric shaft duration. This amounts to as many as six sparks at idle, and as little as two at high rpm, but no matter how many times it fires, the spark always lasts for a full twenty degrees. This is the best of both worlds, a high intensity, long duration spark. Just about every racecar on the planet has one, and you should too.
I have installed many MSD's, and the results were always more power, better driveability, and better gas mileage. A second or third gen. will require three boxes for the entire ignition system. This is quite expensive. You can make a large improvement by simply buying one box for the leading, and the results will be even better if you replace the stock dual coil with two MSD Blaster coils. Simply run both coils from the same MSD box. The ultimate setup is of course three MSD 6A's, and four blaster coils, but this will set you back about $700, and you probably will not fit all of this under the hood.
Well, that's about it for the second and third gen RX's. I am currently testing spark plugs, and I will post the results in the future. There is more power here than I thought, especially after I got away from the conventional NGK's. As soon as I have some dyno results, they will be on the page.

Distributors Suck

Now for the first generation. Distributors suck! Distributors require that the charge jump a .075" gap from the rotor to the cap before it can even fire the .055" gap of the spark plug. The gap in the distributor cap is easier to fire than the spark plug gap, because there is much less pressure, but it is still a really shitty way to make fire. Luckily it is relatively easy to convert the leading ignition to direct fire. I finally got around to doing this on my 13B, and then I was mad at myself for not doing it sooner.
Before the conversion, I was using an MSD 6A, with an Accele super coil. This is a lot of juice, so I was really surprised at the improvement after converting to direct fire. I called MSD to be sure that their box would fire two coils, and their tech guy said "Hell, it would probably fire a whole row of coils." I set it up with two stock coils for the leading ignition and was stunned at the results. The engine made more power everywhere in the powerband, and the driveabilty improved dramatically. I will never again run an MSD through the distributor.
Here's how it works. All you need is an MSD 6A, and an extra coil. Two for the leading, and one for the trailing. Trigger the MSD with the magnetic trigger inside of the distributor.Do not try to trigger the MSD with the ignitor! The ignitor output is very "dirty", and does not give the MSD a clean signal to work with. Simply cut the green, and red wires that go from the leading magnetic trigger to the ignitor. The leading ignitor is the one facing the front of the vehicle. Connect the green wire from the trigger, to the purple wire of the MSD, and connect the red wire from the trigger, to the green wire of the MSD. Wire power, ground, and ignition as per MSD's instructions. The orange, and black 16ga. wires from the MSD go to the coil. In this case, make two jumpers and connect both coils to these wires. Make sure that the polarity is correct. The stock coils are labeled positive and negative. The orange wire goes to positive, the black wire goes to negative. Do not screw this up! The same goes for the magnetic trigger in the distributor. If you wire the trigger backwards, the timing will be advanced by approximately thirty degrees. Now simply run a plug wire from each coil to a leading spark plug. It doesn't matter which one, because they will both fire at the same time. Leave the trailing ignition just as it is.
This is referred to as a "wasted spark" system because eack rotor recieves an additional spark during the exhaust phase. On a rotary, this extra spark is actually beneficial, because it fires at the trailing end of the chamber which is where most of the unburned fuel is concentrated. Igniting this fuel will not make more power, but it will clean up the emissions slightly. DO NOT try this setup on the trailing ignition. Because of the different spark plug location you will ignite the incoming mixture from the next stroke. At best, you will lose power, at worst, you will break apex seals. If you have any questions about this, feel free to send a message. This is a simple wiring job, and the results are amazing. This is cheap power, and the improvement in gas mileage will probably pay for the MSD in a years time. I have not tried this with upgraded coils, but when I do, I will let you know if there is further improvement. I am only sorry that I didn't try this on the dyno so that I could measure the improvement in horsepower. Next time I have a 12A on the dyno, I might do a comparison, and post the results.