The most effective way to make the VTEC crossover point louder is to install an aftermarket air intake on your Honda engine. Stock intake systems feature a closed-off air filter and as a sound-deadening acoustic design. Aftermarket air intakes that feature an exposed air filter substantially increase the engine volume. Since the air intake is connected in close proximity to the engine head, the VTEC crossover point is especially emphasized, as the crossover noise is due to the engagement of larger camshaft lobes that are just inside the cylinder head.
Acquire an aftermarket air intake. To make the VTEC crossover as loud as possible, you want an air intake that features an air filter that is exposed because it transmits the maximum amount of engine noise. Common aftermarket intake types include cold-air intakes and short-ram intakes. Cold-air intakes feature metal tubing that locates the air filter outside of the engine bay area. Short-ram intakes have the same design and function except with shorter piping, thus the air filter remains inside the engine bay.
Open the hood of your vehicle, and locate the stock air intake system. The end of the intake tube is secure onto the engine throttle body. On Honda engines, the throttle body is located on the opposite side of the engine as the exhaust outlet. Stock intake designs vary, but, generally, the intake system has a black intake tube that leads into a larger black box in which the air filter is located.
Loosen the hose ring that secures the intake tube to the throttle body. Remove any mounting screws along the plastic intake system assembly that secure the intake onto various parts of the engine or chassis. Disconnect any sensors mounted into the stock intake system. The entire intake system can then be worked free of the engine bay. Carefully lift out the stock intake system and set it aside in case you want to reinstall it in the future.
Fit your aftermarket intake system in place of the stock unit. Fit the aftermarket rubber hose adapter onto the throttle body, then slide the end of the aftermarket intake tube into the adapter. Secure the adapter with the supplied hose rings. Secure the aftermarket air filter onto the opposite end of the intake with the supplied hose ring. If applicable, install any supplied mounting screws that secure the aftermarket intake to stock mounting locations.
Plug any stock sensors you removed from the stock intake into their designated locations on the aftermarket intake system. Check that all sensors, screws and connections are secured to achieve an airtight seal. Close the vehicle hood, and start the engine. Rev the engine a few times to ensure normal engine function. Drive your Honda on a roadway that allows for safe and legal acceleration to the RPM redline of your engine. Accelerate your engine under full throttle. You hear a louder, throatier engine note and a louder and more powerful VTEC crossover.
