BF - BF is the chassis designation for 323's in the 1986-1989 model range. Any 323 made during this time frame is referred to as a "BF 323". Note that between 1987 and 1988 the BF 323 recieved a minor front end facelift, including redesigned headlights and a smaller grill.
BG - BG is the chassis designation for 323's in the 1990-1994/5 model range. Any 323 made during this time fram is referred to as a "BG 323". BG 323's were only available as hatchbacks - any sedan versions of the 323 made during this time frame were given the model name "Protege".
B6 - The B6 is the common engine found in the BF (1986-1989) 323s. The B6 is a 1.6L SOHC 8-valve normally aspirated engine rated at 82hp from the factory. The "B" stands for the Mazda "B" series block used in the engine, and the "6" comes from the 1.6 liters of displacement.
B6T - The B6T is the engine found in the BF 323 GT and GTX, as well as the early 90's Mercury Capri XR-2. Like the B6, it uses the Mazda B series engine block and displaces 1.6 liters, but the B6T has the added benefit of an turbocharger/intercooler setup. The B6T has a DOHC cylinder head and is rated at 132hp from the factory. The only main difference between the B6T's block and that of the non-turbo B6 is that the B6T has oil squirters in the cylinders to aid cooling.
BP - The BP engine is the common engine found in the BF (1990-1994) 323. It uses a block design which is virtually identical to the earlier Mazda B series block, but one which is physically longer in order to support more displacement. The BP engine displaces 1.8 liters, and can be found in SOHC and DOHC versions.
BPT - The BPT is the engine found in the BG 323 GTX/GTR, and was never available in North America. The engine uses a DOHC cylinder head, and comes in two versions - a 185hp GTX version, and a 210hp GTR version. The differences between the GTX and GTR include stronger internals and a beefier turbo in the GTR version.
DX - This is the base model of the 323. The DX's had very few options. Usually they don't have a passenger side mirror, and some came without A/C.
SE - This is the first step up. The SE's had a few options, and usually came with both side view mirrors. A little bit nicer than the DX. Some were labelled "Sport", but as far as I know, there is no difference between an "SE" and "SE Sport".
LX - This is the "luxury" model of the 323. The LX came with nicer upholstery on the seats, nicer (upholstered as opposed to vynl) door panels, and nicer carpeting. Usually the LX came with a center console, and some even had sunroofs. Another way to tell an LX from a lower model was that the side view mirrors were painted to match the body, and the trim around the windows and the center pillar were painted black, like the GT and GTX. Usually had alloy wheels instead of hubcaps, and had an optional tire size that was slightly different from the base models.
GT - Usually a GT refers to a limited run 2WD turbocharged sedan version of the 323 that was only available in 1988 (some claim to have seen 1989 models, but all the literature I have seen over the years points to the turbo GT's availability being limited to one year). However, in Canada, some dealers converted some base 323 hatchbacks in to "GT" hatchbacks in '86 and '87. These GT hatchbacks still had the SOHC non-turbo engine and were front wheel drive, but they added a lot of the higher-end options only available on the turbo models (which at the time were only available overseas), such as the sunroof. The GT hatchbacks usually have a "GT" decal on the side of the car. The turbo GT was only available as a sedan and came with all of the high-end options from the LX, as well as some other goodies such as an optional adjustable suspension, which was controlled via a switch on the dashboard and could switch between a "normal" mode, one which gave you a slightly better ride quality, and one that was firm for better handling. The turbo GT's also came with different bumpers, with openings in the front bumper to aid cooling on the intercooler and radiator. The bumpers' styling was slightly different from the non-turbo 323s, and were painted to match the body.
GTX - The GTX was made from 1986-1994, but was only available in North America in 1988 and 1989. The GTX was a 4 wheel drive, turbocharged and intercooled hatchback. The GTX was made because of the homologation rule in WRC rallying. The GTX was basically a seriously de-tuned rally car for the street. In North America, only 1,243 were sold, making the GTX a rare car. The GTX had the luxury options from the LX, as well as the extra goodies previously mentioned from the turbo GT (minus the adjustable suspension). There were side skirts available for the GTX from the factory, and the GTX also had two hatch spoilers - one at the top and another at the bottom.
GTR - The GTR was even more limited in production than the GTX. The GTR got a souped up version of the BPT engine, and was basically ready to race straight from the showroom floor. 210 horsepower - nearly unheard of at the time - and 4 wheel drive was all you needed to know about this bad boy.
GTAe - GTAe refers to an EXTREMELY small number of GTXs/GTRs that were modified and built to be used specifically for rally racing by Mazda. That is, these cars were not intended to be driven on the street.
1) Does anybody make a cat-back exhaust for my 323?? - If you have a GTX, HKS makes a bolt on cat-back exhaust. Otherwise, the answer is no. But, all hope is not lost - most local muffler shops will make custom bent cat-back exhausts with whatever size pipe and muffler you wish to use.
2) What size exhaust would work best on my 323?? - That depends. On a non-turbo 323, you will want to stick with 2"-2 1/4" diameter piping. You could get away with 2.5" if your 323 is heavily modified, but generally speaking you'll want to stay with no larger than 2 1/4" pipe to keep from losing your bottom end power. If you have a B6T powered 323, 2.5" piping usually works best. If you have a lot of modifications, you'll see more top end power with 3" piping. A BPT powered 323 works bestt with at LEAST 2.5"-3" diameter piping. There are a variety of aftermarket mufflers that will work with the 323.
3) What engines can I swap into my 323? - It depends on how much money you want to send on custom fabrication. But if we're just talking about basically bolt-in engine swaps, there are a few options: BF and BG 323's can handle the B6 and B6T without any major problems. The BF and BG 323 can also accept the BPT engine with some minor fabrication. Another option is the KL-ZE, which is a Mazda 6 cylinder engine. Of course, the KL-ZE requires some major fabrication to work in a 323. 13b rotary engines have been successfully transplanted into BF 323's as well, but again this requires extensive fabrication. There are probably other engines that will work if you're willing to spend the time and money on the fabrication necessary to make it work.
4) Does anyone make an intake for my 323?? - Finally, the answer is yes. For the BF 323, Cubed Productions makes an aftermarket intake tube that runs from the throttle body to the MAF. You can also get an adapter that allows you to remove the stock air box and run any type of K&N or HKS style aftermarket filter that you like. It should be noted that Weapon-R developed an aftermarket intake tube for the BF 323, but it is unknown whether or not it is actually in production. For the BG 323, there are a few companies that make aftermarket intake tubes that work with the BP engine. Adapters are also available to replace the stock airbox and run an aftermarket air filter.
5) Does anyone make clear corners/lenses for my 323?? - There are no aftermarket clear corners (or tails) for the 323. However, in Japan and Europe the BF 323 came from the factory with clear corners. The difference between the Japanese corners and the European corners is that the Japanese corners have a small protuding amber rectangle on the side of the light, whereas the European corners are completely clear. However, to get the Japanese or European corners to work on a North American 323, you also will have to have the Japanese/European headlights, which makes this swap fairly expensive. The reason for using the Japanese/European headlights is because the Japanese/European corners are wider than the North American corners. As a result, the Japanese/European headlights are narrower than the North American ones. So, if you try to use the wider North American headlights with the wider Japanese/European corners, the corners will hang off the car. You'll also have to make an adapter to get the Japanese/European headlights to work with the North American wiring, but this is fairly easy to do. You *can* get aftermarket clear turn signal lenses though. They are fairly inexpensive and are available through Corksport and other suppliers.
6) Will a DOHC cylinder head from a B6T fit on my non-turbo SOHC B6 block?? - Yes, but it's not worth the trouble. There are several complications with doing this head swap. The first problem is that the DOHC head has oval shaped intake and exhaust ports, whereas the SOHC head has tear shaped ports. So, this means that your intake and exhaust manifolds from the SOHC engine will not work with the DOHC head. So, you have to swap to the DOHC intake manifold, which isn't too bad if you can find one - but now you have some other problems. If you're trying to swap the turbo setup onto a B6 block, you can use the B6T exhaust manifold turbo - otherwise you may have to custom fabricate a non-turbo header for the DOHC head. Once you solve that problem, you're going to have to swap in pistons for the DOHC head - your SOHC engine has pistons made for the original 8 valve head - so they're not cut to handle 16 valves from the DOHC head. So you're either going to have to swap in B6T pistons, or have some non-turbo pistons made that are cut for 16 valves. If you just swap in the B6T pistons, you'll also have to swap in the rods, as they're a bit different and not compatible with non-turbo rods. You'll also be losing a little bit of compression unless you're running a turbo setup, because the B6T pistons run lower compression than the SOHC engine because of the turbo. Finally, if you overcome all of these obstacles, you're going to have to swap in a bunch of pulleys, belts, and accessories from the B6T to get it all to work properly. SO, the bottom line is, it CAN be done, but you'll probably spend as much money as it would cost to buy a complete, running B6T, and it will be much more aggrevating than just swapping in a B6T, block, head, and the whole nine yards.
7) Can I swap the 4WD drivetrain from a GTX into my non-turbo 323?? - No. The reason for this is that the GTX used a floorpan that was different from the GT and non-turbo 323's floorpan. The GTX's floorpan has a larger tunnel which allows passage of both the exhaust piping and the driveshaft to power the rear wheels. The GTX also used a different "saddle" style fuel tank that allowed the driveshaft to pass through it. The non-turbo 323 hatchbacks have a tunnel that is barely big enough for the exhaust to pass, and there is simply no room to run the driveshaft. The only way it would work is if you could weld a GTX floorpan onto the non-turbo body, and even then you'd still have to swap to a a GTX fuel tank and possibly other bits as well. It's just not feasible.