Maybe I'm a little late. I "got to downgrade" from an 03 F150 SuperCrew lifted 4X4 to a fuel efficient '05 3 Wagon. The only upgrade I have on my 3 is a Borla catback exhaust. I'm looking to get spark plugs, lowering springs, very upgraded tires and a CAI. I love driving my car, I save soooo much on GAS. I just hope I don't make up for it in tickets! lol

 

Hi softballguy!! Welcome to MazdaForum and the Mazda community in general.

Tires! GREAT idea. Tires will make a huge difference in how the car handles, accelerates and brakes.

Lowering springs are also a great idea. Eibach's are said to have the best ride and considered to be among the best overall. I can tell you that my H&R's ride a little hard.

CAI? Well, if you have an unlimited budget or want to clean up the engine compartment, otherwise don't waste your money.

 

I certainly am not rich. With the airflow to through that big Borla exhaust, it almost sounds like it is not 'breathing' right. If that makes any sense. I've been thinking about the Continental ExtremeContact DWs. I need to replace the shocks and struts. The idea for the Eibachs are because of the space between the tire and the wheel well and hopefully for a better ride and grip.

 

A CAI will do almost nothing for you... unless you plan on driving the car a +4k rpms all day long. Chances are your spark plugs need lookin' at (as you'd said,) though they are iridium and should go @ least 75k miles. And perhaps a throttle body cleaning is in your near future too.
Avoid using chemicals on that if you can. They often do more harm than good. A clean dry rag is your best option here, perhaps with a little MILD soap, such as dish detergent.

You can also try the Monzta Advanced Timing mod and see if that helps. It's free and takes about 15mins.

I have the Vibrant system on mine, and its been said the Borla is similar in both sound and performance. I bought a NOS Mazdaspeed (AEM) CAI from a member of another forum for "cheap." I like the way it looks and how it cleans up my engine compartment, but as far as day-to-day performance is concerned.... As I'd said before, don't waste your money. It is often the first mod people do, but the return is not good for the investment, imo. You can find better ways to spend $250 than a tube with a filter on the end of it.

Spend it on suspension pieces... shocks/struts, a rear camber kit, springs and a HEAVY rear sway bar. I suggest the 27mm Racing Beat bar (OE is 20mm) as the best I have tried so far. You will need heavier links for that bar though. There are some aftermarket ones available from AWR (what I have) and one or two others, but some are running OE Mazdaspeed3 rear links as well.

If the budget is there, look into the Koni FSD system as well. If wanting better handling and don't mind a slightly harder ride, the Mazda5 kit will work on your 3. It is designed for a slightly heavier vehicle, so the spring/dampening rates are up from the 3 kit a bit.

Get a rear camber kit, preferably and adjustable one (e.g. SPC) and have an alignment done. Have them set the rear camber at +/- -1* for better tire wear and rotate them regularly or you will chew up tires.

I am currently running DWS's on mine. The wear rating is GREAT (540-560?,) have GREAT traction both forward, braking and in rainy weather (NO hydroplaning so far.) These are in many, MANY ways much better than any other tire I have had on this car so far. But they is not what I would consider a true high performance tire either.
The sidewalls are soft, even w/6 more psi up front and 4 more in the rears. I got tired of replacing expensive tires in less 20k, and since I am not racing the car I thought I might give these a try. We also have a set on the wife's Vibe.

 

Wow, that is an enormous list of suggestions! Thanks a lot! lol A lot of options. My car is an automatic, but it is fun when put in the sport shifting mode!