There are really no good HS Mazda3 threads that discuss all the prep you can do in detail, so I figured I'd start a thread where we could compare notes and talk about Mazda3 prep for H-stock. This could be used as a guide for people wanting to know more about HS prep. I'll start by sharing my setup and what I have learned the past few years and I hope it is helpful to some of you competing or wanting to compete in HS. I'm a highly visual person so there will be pictures coming
Feel free to ask if you have any questions.
I start with the basic stuff first.
Air filter: Got the K&N which is obvious and most popular choice. Easy "free mod" basically. Saves money and maybe gives a couple hp at the high end of the rpm range.
Brake Pads: I've been running EBC Yellow pads on the front and Hawk HPS on the back. Very happy with the setup. The EBC pads have impressed me greatly. Very powerful bite, 0 squealing on the street once past the break-in period, very good bite when cold, even better bite when hot, they do put out dust but nothing real crazy. Just a great pad for a daily driver that is also autocrossed. These just flat out stomp the stock pads or HPS pads in terms of brake torque and initial bite. With stock or HPS up front sometimes I could stomp on the brake and not lock a wheel (with race tires). If under maximum braking you cannot lock a tire, you are probably leaving some braking performance on the table. Maximum braking occurs just before lockup. No longer an issue now and I'm able to utilize all the stopping ability of the race tires. The Hawk HPS pads work well as rear pads since less brake torque is needed and also rear brake temps are considerably less.
Tires: I've tried just about everything out there, V710's, Hankook Z214, Hoosier A6, and BFG R1-S. I'd say my current favorite is the BFG R1-S. Great stick, competitive down to the cords, decent life, and if you do Tours, they have the best contingency in the Biz right now. Just be sure to use enough pressure as they seem to need more than the others. If you run too low they will cord and die fast. I have found around 50 psi works well with them. The Hankook C71 compound is a great tire as well and the best value, just no contingency. For locals, I like the C71's, for Nat Tours, I like the BFG's. I've used several sets of Hoosier A6's and have never been greatly impressed and think they are a bit over-rated and overpriced. I run the Kooks and the BFG's in the size 245/45/16.
Wheels: HS legal wheels for the Mazda3 are hard to come by. If you have a hatch with the 17x6.5" wheels you are pretty much out of luck in the lighweight wheel arena. The Sedan's have a few more options. My 2006 S model came with the standard 16x6.5" wheel. Not a bad wheel. Weighs about 17.5 lbs or so. However, I wanted something lighter and found the 16x6.5" Rota Boost wheels to do the trick. They weigh 15 lbs on the nose. One thing with the Rota Boost is that the offset is 46 mm. Stock offset for the Mazda3 is 52.5 mm. The Rota's are just ever so slightly outside of stock offset rule. You would probably be fine with these wheels as is, especially for local competition , but I didn't want to chance it as people get protested at NT's for sometimes seemingly insignificant things all the time and I wanted to make sure the car is bullet proof legality wise. In order to make the wheels 100% for sure legal, I had the mounting faces on each wheel milled down (effectively increasing the offset) until we got them to where they needed to be. I also run the stock wheels as well at some events. Since the stock rules dictate 1/4" or 6.35mm offset difference is allowable many people run spacers. I run some Eibach 5 mm spacers with the stock wheels. This effectively widens the track almost 1/2" and also allows running wider rubber without rubbing issues. I also can get enough turns with the stock studs and lugnuts so replacement studs are not necessary with the 5mm spacers, but you can certainly do longer replacement studs of you prefer.
Sway bar: Ok, still some debate about which sway bar to change, if any, but it seems most have settled upon changing the rear sway. I personally like the car better with the rear sway on and I believe it holds some advantages. I have tried two aftermarket sway bars. First one was the adjustable Corksport bar. I found neither the bar nor the brackets that come with it, suitable for hardcore AX duty. Both the bar and brackets deformed/bent. Anyway, Corksport was gracious enough to return my money. After the Corksport bar I went to the Hotchkis 32mm rear sway and also bought the heaviest duty sway brackets they make (extra on the side). I am very pleased with the Hotchkis and think they make a great product in both the bar and their beautifully crafted, high quality brackets. It has been holding up great and does what I want it to do. Also decided to purchase some MS3 endlinks, they have a beefier than the standard endlinks and the originals starting to get worse for wear after 150K miles but are still functioning fine (rubber boots are slightly torn). I wanted a reliable setup so I went with the OEM MS3 endlinks. There are aftermarket adjustable endlinks out there for our cars, but the reviews were not looking promising. Many said they don't hold adjustment or just plain break and the hardware that came with is just plain cheap. Most of them are made in Taiwan...I don't like parts that are made in Taiwan.
Shocks: There seems to be two clear standouts when it comes to shocks for our cars, Bilstein and Koni. I decided to go the Bilstein route and purchased the B8 sport struts/shocks for the Mazda3. They have been a real workhorse for everyday driving and also very nice on the AX course. They are quite a bit firmer than the OEM shocks. I have thought about getting them custom valved by FatCat Motorsports, however I feel the ride quality right now is a good compromise between everyday driving and AX firm. Koni singles aka yellows are very popular and decent shocks, but adjustment primarily affects rebound. In HS upping compression is vital to compensate for soft springs. The ultimate shock setup would probably be a set of Koni DA's or double adjustables. Rear adjustment on the singles or doubles is a pain on the Mazda3 and can't be done on the fly unfortunately. I've been very happy with the Bilstein sport shocks so I'll be sticking with them more than likely.
Exhaust: This leads me to the latest develop. Just ordered a Borla exhaust system and got it in. I should have it installed in about a week once I get time to go over to a friends (who has a full lift) and get it done. What drew me to the Borla is the nice deep tone, no high pitched buzzing here. Also very little resonance when cruising making it a good exhaust to enjoy on a daily basis.The Borla should produce some weight savings and also a nice little bump in HP. Straight through flow technology with no baffling. I'll give my impressions once installed.