Intake
(can cause warranty hassle)
The OEM intake is really VERY good. The only 2 aftermarket intakes that can boast a power improvement are the Mazdaspeed and AEM. Which happen to be the exact same thing, just with different logos. That intake can give you a very slight bump in power. And I mean very slight. Within the 2% error margin of modern dynos. (2% of 180rwhp = 3.6hp). There are a few other intakes that are net equal to the OEM intake. Every single other intake, from K&N to ebay kits, cold air and ram air, complicated and simple, every single one will cause you to lose power. This is because they do not have the proper R&D into how the air flows into our engine. They just fabricated a tube, made a port for the MAF, and jammed an air filter on the end. The air becomes heavily disrupted, the MAF can't read it right, and the ECU believes what the MAF is incorrectly telling it, causing the ECU to over and/or underfuel the engine all over the rev range. Even removing the OEM screens can cause power loss, since those screens are very well designed to straighten the air flow and smooth it down considerably. They aren't there to 'catch rocks'. Just to straighten the air flow.
The filter isn't even bad. There is FAR more breathable surface area on the OEM air filter than nearly every intake kit out there. The OEM filter is NOT a restriction on the air flow. The K&N drop-in panel was dyno'ed by Speedsource to show a consistent 1HP increase vs OEM. However, the K&N's filtering is substandard, and in Daytona races (Grand-Am ST class), they were losing engines to sand ingestion. 1HP is not worth that risk, especially if you are paying for it. Stick with OEM. The only solid reasons to go after market are:
- the subjective reason of "I like the sound"
- the cooling reason of removing the OEM air box to improve air flow from the radiator
- or the improvement in how easy it is to get to any items under the OEM air box.