Stock Airbox Modification

The stock airbox is restrictive, but it is designed to keep induction noise to a minimum. These modifications increase the airflow a little. Probably not enough to be felt, but enough to be measured on a dyno. Induction noise does not seem to increase. We have measured about 2-3 hp on a stock RSX and about 4-5 on a boosted RSX type S.

Tools needed:

• 10 mm and 8mm socket
• Hand held hacksaw
• Side cutter pliers
• About an hour

Remove the airbox from the car. Before starting, turn the airbox upside down and note the deep division running between the two chambers. If you cut too deeply, you will break through into this area. Cut along the plastic marked in orange. This chamber we are opening up is designed to reduce induction noise. Previously the air was directed at high velocity down one side of the filter - which is quite restrictive.

Using a pair of sidecutter pliers remove the 4 ribs marked here. This allows the air to more easily move around the back of the filter.

The result of these modifications is that the air as it enters the box expands and slows down, which makes it easier to enter the filter.

Where to go from here? You might try to make a cold air pickup to feed into the stock airbox.