Review on AEM 21 690C Cold Intake System by Dan Bobbert

I have this air intake on my 2007 S2000 and am very happy with it. In general, the unlimited cold air you can feed the engine, the more power you will produce. This air intake does a great job of drawing in cold air because the filter is right in front of the radiator. The standard intake depends on the air under the hood, which is always much warmer than the outside air. This is an even bigger problem when the car is not moving. A phenomenon known as "thermal soaking” can then occur, increasing the underhood temperature even higher and further reducing OEM intake performance. This air intake avoids these pitfalls by drawing air directly from the outside. With this air intake, however, you must be careful not to submerge the filter in water while driving. If the motor swallows water (hydraulic lock), it can easily be damaged. Small puddles and downpours aren't a big deal, but driving this water shovel through 1 foot of water will get you in trouble. AEM sells a bypass valve (highly recommended) that can be added to the inlet line to keep water out. They also have a waterproof "sock" that can be worn over a filter that repels rain and other water mist. However, I suspect that this also reduces the airflow somewhat. So functionally I give it 4/5 stars, with one caveat to watch out for deep water. The Honda S2000 is so good straight from the factory that you won't get much performance with this or any aftermarket intake, but you'll gain quite a bit with a custom tune. The main benefit is improved sound. The OEM intake really muffles the sound of the engine, while this air intake really makes it roar. You will be amazed at the noise your engine can make when you open the intake valve. It makes as much difference to the sound as the exhaust (and without the exhaust rumble!). So for the price of this recording you get MUCH better engine sound, a little more power and less engine heat. However, I would recommend pairing this with an AEM bypass valve.