To the best of my knowledge, this page accurately describes the procedure that I followed to install an ITG foam air filter panel in my 2000 A4 1.8TQ. Although all '96-'01 A4's use the same size filter, I cannot confirm that this procedure will work for your car and filter.
Use these instructions at your own risk.

• Phillips screwdriver for removing heat shield.
• Gloves to protect your hands from the razor sharp edges of the heat shield and surrounding components.

 

1. Remove components blocking access to the airbox.

Unveiling the airbox The airbox is obscured by the plastic air snorkel and cover. Grab the edges of the cover and pull straight up. Slide the front end of the snorkel away from the front of the car. Pull straight up on the back end of the snorkel to free it from the airbox.

2. Remove heat shield.

Heat shield is held by 4 screws Two of the four airbox clips are partially obscured by the heat shield. Removing the shield will make access to the clips easier. Undo the four Phillips screws holding the shield. The two bottom screws are difficult to reach. If you have skinny arms, you can reach into the engine bay with a mini-screwdriver, or use a screwdriver with a long, thin tip. The heat shield

3. Detach EVAP valve.

A rubber tab holds the valve to the top of the airbox Detach the EVAP valve and hose from the top of the airbox.

4. Undo the airbox clips.

Yellow arrows point to the airbox clips Four silver clips hold the top of the airbox. Pry them away from the top of the airbox. The clips will remain attached to the bottom half of the airbox.

5. Remove the old filter.

Slide the old filter out Gently lift the top of the airbox. There are still some hoses attached to the front of the airbox which prevent the top from being completely lifted off. Take care not to stress any hoses still attached to the top of the airbox. The old filter can be pulled right out of the airbox. Stock paper air filter

6. Install the new filter.

Slide new filter into the airbox Some filters may require preparation before installation. Most are pre-oiled. Refer to the filter manufacturer's documentation for instructions. While still lifting the top of the airbox, slide the new filter in. Aftermarket filters are made to fit very tightly, so you will probably have to spend a few minutes adjusting the filter so that all the edges fit inside the airbox. Take care not to let the oily filter touch the mass air flow (MAF) sensor which sits inside the airbox.

7. Reassemble.

Close the top of the airbox, clip it down, and reinstall the heat shield and hoses.

8. Clean pre-filter trap.

Pre-filter trap At the bottom of the intake duct, where the snorkel attaches, there is a screen which traps large pieces of debris. Clean it out with a shop vac then reinstall the snorkel and cover.