Originally Posted by NoPistons

Apex seals are made in usually 2 or 3mm and are located at each corner of the rotors. Mazda, atkins, ianetti, hurley, rotary aviation, and racing beat are basically the major manufactures of apex seals that are used in the U.S. some misconceptions about apex seals are that they are weak, cannot seal under high boost apps, and are otherwise plain unreliable. All of these descriptions have been trialed and tested to be false. Another misconception is that 3mm seals are stronger and will be less prone to fail at minor detonation than the standard 2mm. Basically what many people think of them is that they are just "too much money to think about." In other words to use 3mm seals you must first mill your rotors (excluding engine years 74-85) to make them fit. Plus the benefits (none have yet been found) are clearly underscaled to the price of the seals separately.
Many seals are made of different composites or alloys to fit specific applications. The highest quality seal you can buy for a "standard" application is the stock 3 piece 2mm seal. Most people say "when in doubt, go with the stockers." Time and time again many people using these seals for a daily driver as well as high hp race engines have found good success and reliability in them. Some downfalls people have found is that even though they come from the factory looking like a 2 piece seal, the corner section piece is only glued on to the bottom half making it easier for installation. After the first couple of cranks the corner section breaks off and seats to help seal better at low rpms making idle and startup an easier task. But by having the freedom to adjust in their slots the large apex seal spring usually pushes the corner piece to sit askew consequently scratching the hell out of the very outer edges of the rotor housings. If you are willing to give up the slight sealing advantage of a 3 piece, 2 piece seals seem to take care of this problem. Another negative is that at high rpm stock seals have a tendency to vibrate or chatter in their grooves because of their heavier weight, which in turn make chatter markings on the rotor housings chrome surface. Both of these symtoms usually occur after many miles and are more of a long term reliability issue than any other.
On the other end of the spectrum ianetti ceramic apex seals are manufactured for specifically the racing type of engine. They are made of light weight ceramics which are designed to handle high temps that big boost and high rpms will cause. Although the seals are made for big hp applications they will still explode on detonation just like any other seal. The only difference with these are that they will most definitely cause damage within the housings and irons if not tear your turbine wheel to shreds. Based off of those facts they are not "recommended" for forced induction setups. Ceramic seals are more of a give and take situation when it comes to using them. They take much more stress of heat from the previously mentioned causes, and many builders tend to tune their afr's leaner to take advantage of this. Ceramics also give the option to run upgraded apex seal springs to reduce the occurence of seal chatter because of their lightened weight. But you will pay the price of not only the expensive seals but for the new housings that they require before installation.
Some more middle ground and popular apex seals would be both the atkins and rotary aviation units. Both of these seals have proven to hold their ground on high revving n/a bridgeports and as high as 42psi of boost in extreme cases. Some characteristics of the atkins seal reveal that they are not as brittle as the stock units and are good for quick break in periods. The rotary aviation have been refreshed and many serious builders have taken a leap of faith on them and have found great performance out of them. An interesting fact, the rotary aviation seals are the only units to be life-time warrantied in a stock application using new rotor housings. This feature has only been evident on the stock mazda seals. Either way you look at it, both brands are great choices for just about every application. but some builders have warned to make sure to give some extra clearance for both seals tend to have mucho metal expansion under serious loads. By giving the extra time to clearance your seals out you can dramatically improve performance and reliability.
The main point of choosing the right type of apex seal is to fit your setup and goals. If you want a nice daily driver go get some stock units or 2mm hurley seals, if you want 450rwhp at 15 psi go for some rotary aviation or atkins. But if you are going for that n/a peripheral port race engine and revving to 10k "bring the big checkbook" and look for some ceramics or carbon aluminum seals. whichever way you go, to achieve success and reliability in modified rotary engines your tuning and clearancing is key!

Originally Posted by Blake

Without exception, nobody makes a better metallic seal than Mazda. Period. All the aftermarket stuff have shortcomings. Some are useful for limited applications, like breaking-in and tuning an engine before upgrading to ceramics, but I would not give 20 bucks for a set of anything out there today. We find them in all sorts of 10K wonders (usually because the engine was rebuilt with Viton oil control o-rings, which suck for that application) and just toss them in the garbage. It is no exaggeration to say, the difference is as significant as Snap-On tools to Harbor Freight tools, except the premium is less. There are no Craftsman or Husky tool analogies, where you find a balance between price and performance. You either buy the best or you buy crap. Crap always costs less but that doesn't mean it's a good value.

Ceramic seals, on the other hand, are a whole 'nuther ball game. There are two excellent manufacturers: Ianetti and NRS. Ianettis are more expensive, but no other apex seal has won Le Mans outright! NRS are arguably just as good at a more reasonable price. They also make a greater variety of seals for different applications and listen to the engine builders' advice (we suggested a different end piece angle to improve strength...and they did it!).

Originally Posted by BlastinSideways12A

Just buy my brand new OEM apex seals with brand new springs, still in the packaging for 325 shipped. ;p

Originally Posted by FJDRX7

I use Atkins with no problems so far, and they do some R&D for them, they might not tell you about what they use "the metal", is like Coca Cola publishing on the net the secret formula, LOL