Project Mazdaspeed3: Building a Stock Class Cone Killer- Introduction and Installing Koni Shocks

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To complement our lightweight wheels, we picked up a set of ultralight Skunk2 forged aluminum lugnuts. Our original nuts had been hit with an impact gun of the wrong size, and the heads were mangled. The Skunk2 nuts are crazy light, weighing a scant 23.5 grams a piece. Skunk2 forges these nuts out of 7075 aluminum and then ahrd annodizes them for long life, making these ideal for our MS3- shaving weight and looking great against our sweet new wheels. The downside is that you can no longer use impact guns on these nuts, but that’s a small price to pay for saving weight, right?  We also picked up a cheap 18” breaker bar and non-marring 17mm socket to keep in the trunk as the Skunk2 nuts use a smaller socket than the Mazda nuts.
 

A set of autocross only wheels makes for great spares when you find a TPMS sensor is leaking and need a quick spare to get you through the day. I do not recommend this, as the car pulled left all day long.  

Air Filter

SCCA rules allow for a high-flow, factory replacement style air filter, provided no other modifications are made to the intake tract. Our choice was easy- we went with an AEM DryFlow filter. AEM filters were developed in collaboration with K&N, so you can be sure you’ll get more performance without a loss of filtration. The AEM filter does not need to be oiled when it is cleaned, making service super easy. Best of all, AEM's filters come with a lifetime warranty and never need replacing. In the 3, the AEM filter drops in without the use of any tools, making it the perfect replacement filter for our needs.

 

The AEM filter on the left versus the Mazda cotton filter on the right. Our OEM filter actually looked to be in good shape, but a touch more power is what we were after, so in goes the AEM!
 
The AEM is a true drop-in filter and fits perfectly into the Mazda airbox. Note that you don’t actually have to remove the top of the box to install the filter, but it’s impossible to photograph the filter with the lid in place. Installation only takes a minute.

Exhaust

A catback exhaust is allowed in SCCA, provided it mounts to the vehicle and exits in the same location as the factory intended. For our car, the original owner did the hard work for us, buying a Mazdaspeed stainless steel exhaust for the car. A true stainless steel exhaust, it reduces backpressure and adds a wonderful sound to the engine.  

 

The Mazdaspeed option exhaust peeks out from the rear bumper.  It is a very subtle exhaust, relatively quiet at cruising, but a screamer when you spool up the turbo. Backfire is very common on rundown. The exhaust is one of my favorite parts of this car. Unfortunately, we don’t really have a lot of specs on this exhaust, as Mazda no longer offers it and any information on the exhaust is no longer available. I believe it is a 3” exhaust made from 304 stainless steel. Most other MS3 catbacks add around 20 horsepower. With no stock exhaust to compare it to, I really can’t say if those claims are true. I can say that after nearly a decade on the road, this exhaust is in great shape: A true OEM piece.
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5 comments

  2. No, that is not true. You can use any size tire you want, that fits on a factory width wheel and fits under the car without any modifications. You can also alter the wheel diameter up/down an inch and alter offset by 7mm.

    My real question is, will 245s fit under the fenders without rubbing?

    Reply

    1. You’re right, I grabbed the rules for wheels, not tires when I wrote this article.

      I wish I could help you here, but I sold the 3 years ago and never attempted to fit anything wider than a 225 under it. Sorry.

      Reply

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